I have a 98 2.8QTip. Can I use springs from a diff year, a 1.8, or Manual shift?

Here's what I think the answers are, but I could be wrong.

For springs, the 2.8 and the 1.8 use different springs. The FWD use different springs than the Quattro too.

For shocks, I believe that the shocks are the same for 1.8 and 2.8 quattros.

For the FWD, the shocks are the same as the quattro for 1.8 and the 2.8, but the rears are different than the quattros.

And yes you can switch shocks/springs from different year as long as it matches your engine/drive configuration. transmission doesn't matter.

Note I'm not entirely 100% certain so take this with a grain of salt.

And I am very glad I did. At the same time I upgraded to 17" wheels and the handling has improved dramatically with some loss of ride comfort. But it is a very worthwhile trade-off.
You definately need to stay compatible between
Q and FWD, but I don't think engine makes a difference.