your alivio system is almost certainly 3x8, no?

deore XT these days is 2x10 and regular Deore is 2x10 or 3x9. any of these will require new shifters in addition to crankset, cassette, derailleurs and chain.

if you're not climbing up big hills, try switching to a narrower range cassette with your alivio and dial the shifters in carefully, and you'll find it quite clean and smooth. I went from an 11-32T 8 speed to a 13-26T 8 speed HG50, and found the closer gear spacings much nicer, and I still have a 28:26 low gear which will get me up most any hill.

re: measurements, you'll need to know if the Front derailleur is a top pull or conventional bottom pull (eg, does its cable come from under the bottom of the bottom bracket, or down the seat tube from the top tube). and you'll need to know the OD of the seat tube where the FD clamps on. 28.6mm is a common size. most newer clampon FD's come with spacers for 3-4 commons izes.