Petlinks Mix-n-Scratch Seagrass Scratch Ramp

My cat is a big boy he is over 20 pounds. Will this hold him and help him up onto the bed without falling over?

The base is in two pieces? I imagine my cat knocking it over very easily. How sturdy is it when a 10lb cat uses it?

Can i buy the carpet section separately from the base and sisal portions of the scratch post? My cat goes through them quickly.

Is carpet on the top?