An 8" is O.K. to view details on the planets. Just don't try to overpower the t'scope or the seeing conditions. A smaller, clearer image is much better than a big blurry blob. You might like to consider buying a 'good' barlow lens.
As for collimation, you can use a film canister,(1~2mm hole in the cap), to start & then buy a 'Cheshire' collimating tube or the Combination sight tube. This has a set of very fine & delicate, X hairs at the end. The normal 'Cheshire ' is all you require & are very sturdy. Take a bit of knocking/dropping etc.
See links for help with collimation, >
http://skyandtelescope.com/printable...rticle_790.asp
http://www.andysshotglass.com/Collimating.html
HTH.
L.
ps. Remember the #1 Rule, Aperture wins. Oh, & don't skimp on E/Pcs. Buy the best you can afford or wait. Just mho. L.