Welcome to Amiga.org!
Congratulations on your purchase. You will find that Amiga.org is the best source of information for your 'classic' Amigas out there.
As for your queries:
1) You could get a new X-Surf 3 ethernet card made by
Individual Computers or search EBay for any used Zorro-based Ethernet card. Try searching the
Big Book of Amiga Hardware for all cards ever made for Amiga and find out what you need. This is an excellent source for all Amiga hardware related questions.
Amiga Hardware Database is very similar, so check that out too.
2) I have a HydraNet ethernet card and it yields 60k cps. Again, check the hardware sites I gave you.
Be sure to use the 'Search' function of this site. So many threads on this topic exist, it's mind boggling.
Enjoy!
