[sick472]

I have only worked on two full suspension rebuilds (two different manufacturers), but I would say that you will need spring compressors. It's just too dangerous not to and maybe impossible without a torch. I don't think the weight of the engine makes much difference. When removing the coil springs, I guess you would not have to cinch the compressors down as much, but what are we talking about...an extra few inches? NBD.

Don't over think it...do it with the engine in or without, you'll not notice any appreciable difference.

If you build the suspension before installing the engine (that's how I've always done it), just get the alignment items adjusted close (eyeballed) and take it to the alignment shop once the project is ready for the road.

A far as torquing the suspension parts, definitely do that as you go. It does not hurt to check it all afterwards, but not necessary.