They are good, but just be careful, there's no one over here that can rebuild them so if they go bust, chances are they'll end up in the bin. Seen a few sets for sale before that have needed a rebuild and their worth next to nothing.
You can use valve springs, retainers, valve guides, valve stem seals from the 4AGE 16v, their all the same. But DO check the spring base pressure as the head might need to be milled or have a valve shim.
BKR7EIX Unless running Nitrous or exotic fuel there's really no need for 8's. I'm sure many of the older members will remember Spuddy's beast, that was using 8's, I think he just switched over to 9's actually when running 600bhp, near enough 3 bar of boost + nitrous + Methanol fuel.
Depends on the spec of the engine, who built it etc. Most forged engines should read about 150-180 really depending on spec. 250 seems a bit high even for a wet test with such low compression motors even stock.
A catch can will be a better setup, filter does the trick but you may find you get some oil residue spitting out every so often. There's many different ways people plumb catch cans though and that's an argument in itself
There's one problem, grade 8 is way way too cold for those mods, you don't need grade 8's till pushing nigh on 500bhp!
Change to 7's, or even 6's will do but might go through them a bit quicker.
Yes you need to block off the original internal wastegate. Best place for them is off the merge collector on the manifold, no sharp bends it should have a nice radius flow to it, otherwise it will cause all manor of boost control issues.
Just change the dampers, their probably not the right ones to support lowering springs/ stiffer spring rate and hence can't control the bump/rebound rates without it feeling bouncy.
Not all superchargers need intercooling, although with that said the only ones I know of that don't need it are the Jackson Racing chargers, what is essentially something along the lines of a Rotrex here it will need cooling due to high rpm.
It will be the 5E-FHE cams, quite rare to find and cost a premium price. They have slightly more duration and lift compared with 4EFTE cams. Not worth the cost that some people ask imo, when you can get custom billet cams for not much more.
5w40 fully synth, consult the engine builder as to what to use as everyone uses different tolerances. They might be quite tight and hence a 5w30 would be better. Generally 5w40 is fine though.