You are probably better off finding a GOOD installer or checking some of the card audio forums where there is more discussion of this stuff. For what it is worth here are some opinions...

Does rockford fosgate suck?

They definitely don't make the highest quality stuff. Popular opinion is that they are geared more towards bass with less concern for sound quality. They are also know for quality issues. MTX probably has better "bang for the buck" in this price range, I would also consider Alpine.

Is there going to be a problem using 100w/rms speakers with a 65w amp?

You may get distortion when you turn the amps up. You are better off sound quality wise with an amp that is too powerful and then keeping the gains lower.

Should I use a smaller amp/cheaper speakers?

The speakers you listed are probably pretty decent (although I have never heard them myself, I have the 4x6s from the same line), but like I said I would look for a little more powerful amp.

Does the basslink suck? Would I be better off with a small box/sub/amp combo? What about those powered bass tubes? I heard they're not very good...

Sound quality wise a small sealed box is your best bet, but I have also heard good things about the basslink. Tubes put out a lot of bass with a pretty small enclosure with the trade off being sound quality. They aren't as tight and the ones I have heard tend to warble (they don't maintain a single tone) under constant heavy bass.

-Mike