How long have you known?

The end of the job is already in the past (as being reported), so the work itself lies '2 steps back', requiring a Past Perfect (a.k.a. Pluperfect) tense; but there also needs to be emphasis on the continuity of the work, as a long hard 'slog'.
Answer 2 is acceptable but does not carry the 'continuous' sense; it reports a mere fact, without any emotional empathy with the poor exhausted workers (such as they surely deserve?).
The outermost Answers, Nos. 1 & 4, incorrectly use the plural form of the auxiliary verb 'have', which does not technically agree with the subject 'team' (a singular entity in itself ~ though clearly, by nature, comprised of a plurality of individuals).

This one is Future Perfect Continuous, because by the (future, yet-to-happen ~ and, no doubt, eagerly-awaited!) point at which Bill will finish his job, he is going to have done almost four decades of steady ongoing work.

This is an alternative way of expressing the Future Perfect Continuous (see Question 2).

This is an example of the Future Perfect Conditional ( ' would ... have ... been ... ')
The 'must' in Answer 4 is tempting, in the sense that 'if Thing A is true, Thing B must follow as a consequence'; but in this circumstance, the 'if' is not valid, since the grandfather is no longer alive. The potential result is therefore not strong enough for a 'must'.

There are a number of 'levels' of timescale and possibility/probability at play in this example: let's 'unpack' it from the point of view of the timings.
'They' would not have arrived (at a time-point one step into the past from when they are telling us about it) without Jules doing some speeding to get them there (obviously enough, before their actual arrival); so the speeding belongs in the Past Perfect (or Pluperfect), i.e. a 2nd, earlier step back into the past.
At that prior moment when Jules decided whether or not to risk breaking the law, s/he was faced with a dilemma: 'Either I obey the speed limit and we risk missing the event, else I could risk breaking the law but we would be more likely to arrive on time'. The Question as we have it takes 'us' back to that dilemma, where the outcome would be conditional upon Jules' decision.
Ultimately, only the Pluperfect Conditional can fulfil all those linguistic duties. Answer 1 has its reasoning inside-out (or back-to-front); Answer 3 is ungrammatical; Answer 4 has the feel of a Romance-language subjunctive clause about it, but lacks any attempt to refer to past events.

He 'might have been considering' any number of options, but when the due time came, any such wish had got him nowhere. In such circumstances we need a compound verb form expressing three distinct elements:
1. It is only possible, and indeed was eventually futile, that he considered such an option at all;
2. Any such consideration took place in the past, so a 'have' auxiliary will need to appear in some appropriate form;
3. He would have spent some continual, repeated or habitual time thinking about his career, so some expression of that continuity needs to be built into the overall eventual phrasing.
Only Answer 2 here 'ticks all the right boxes'; check them!

Only Answer 4 contains the 'continuous' element, expressing how the decision-maker/s were thinking at the time (or during their preparation).
Answers 1 and 3 say practically exactly the same thing as one another, but they each lack that Continuous element; Answer 2 is clearly understandable and makes a bit more effort to suggest both past-ness and possibility, but it is still a less natural version than No.4.

The circumstances here involve the following elements:
1. Negativity ( = lack of proper maintenance, in this case) ... which will need to be borne in mind and incorporated into the final phrase;
2. That the machines already have a backlog of patchy maintenance (i.e. in the past from now) and that this backlog will continue to be in the past until maintenance is reinstated (should that ever occur);
3. That maintenance (or even, lack of it) is inherently a progressive / continuous action.
' ... has not been maintained ...' (with reference to 'now', or, alternatively, the [future] moment of public discovery) would be a reasonable option, but it wasn't offered, and the version at Answer 1 which includes the continuous form 'being' is even stronger and more specific. The juxtaposition of 'been being' may look strange, yet makes perfectly clear and acceptable sense in such circumstances as these: 'My child complained last week that s/he had been being bullied at school', etc. (In this case, there is a use of the 'be' verb as a passive auxiliary.)

The action here spreads over the past and present (and, by implication, onwards into the future); it is also passive. As with Question 8, only Answer 2 here successfully incorporates all of these elements.
Answer 1 suggests that the erosion process is now finished (sadly, not the case; storms in the closing weeks of 2013 have added fresh examples to the baleful classic example at Happisburgh); Answer 3 sounds ~ also falsely ~ as though it suggests that 'we' in the 21st century have managed to put a stop to the erosion. Answer 4 with its present tense at least does not deny that the process continues, but it leaves the historical perspective to the opening adverbial phrase and makes no effort to re-emphasise the continuity.

Answer 1 is not fully grammatical; Answer 2 is grammatically coherent but poor in style; Answer 3 tightens up the 'wasn't able to' to 'could', but misses out the Continuous / simultaneous element (i.e., whether or not he was actually watching at the time when the programme was broadcast).
The alternative use of 'would' in the correct Answer 4 successfully dismisses the possibility, on grounds of logic, while preserving the other three crucial elements of (1) negativity, (2) past-ness and (3) continuity, i.e. the need for a Progressive verb-form.