sum midi keyboard questions

whats up fellas,
i'm new to the mpc game, learned the basics bout the 500, but got sum questions bout midi keyboards, so lets start:

first, is it worth buying a midi keyboard for makin simple melodies or basslines just usin the 500 and the keyboard or are the pads enuff?

i need a keyboard wit midi in and out, right? ( so these http://www.thomann.de/gb/cme_mkey.htm
http://www.thomann.de/gb/maudio_oxygen_49.htm http://www.thomann.de/gb/evolution_mk44 ... yboard.htm are not workin right?

what bout hookin the keyboard wit fruity loops and the mpc to play the samples of fl and recordin wit the mpc? besides i got no own pc in my room, just a pc in an other room upstairs, so i have to take my equip to that room for doin the fl melody stuff

thanks a lot

or maybe savin the money and get sumthin like microkorg later?