On the exhaust bolts/nuts... That's exactly what I do. I haven't busted any yet; maybe I'm lucky, but I think I,m just good (Hehehehe...)
I set the timing mark at TDC when pulling the harmonic balancer (got to use a puller). The cam/crank gear marks are visable ok from the top. Just get a good light down in there. You gotta put the new gears in the new chain (marks lined up) and slide both gears on at the same time. Then pour some oil over the chain and gears before putting the cover back on.
Don't forget the (thin film of) blue RTV on all the gaskets.