a) It's always going to be difficult to find spots to 3-bet bluff as a middle stack at a final table. The bigger stacks can pressure you a lot, and the smaller stacks can force you to either call their reshove or fold, which is often going to end in a fold. It's simply correct to do a lot of folding at final tables when you're 7/8/9-handed and ICM has a significant effect on whether you can get it in preflop for a big chunk of your stack or not. Don't try to force it and end up bleeding yourself down to a short stack.

b) Your calling range should always be dependent on your opponent's shoving range. I doubt there's any blanket adjustment you can make here that would improve things – just make sure you're willing to call off wider in spots where your opponent's shoving range is wide and ICM isn't too sharp. Get yourself a copy of HoldemResources Calculator and run some calculations, it's great practice.

c) No. There's no reason to start including a limping range once you get to the final table. If anything, it's going to make it much easier for other players too pick on you.

d) Sometimes playing tight is appropriate, sometimes it's not. It all depends on the table, the ICM-awareness of the other players, the skill level of the other players, etc. There's no blanket advice here. But if you're having trouble with ICM, then the only answer is to study ICM situations and figure out where the adaptations are that you're not making. The advice above about getting a copy of HRC (or ICMIZER, a good alternative) is probably the best I can offer. A program like that will teach you more than any one forum post ever could.