A concern with doing bass, guitar and keys first, and then adding drums may be that it may make it difficult for a drummer. Not that a good drummer wouldn't be able to do it, but drummers are usually the ones who set the pace. Unless you are rock solid in your tempo as you record everything without a beat, it could cause the drummer problems if he (or she) has to try to anticipate even the slightest tempo changes.
Vocals should be no problem. People sing along with tracks all the time.
You may at least consider recording to some relatively consistent beat like a click track, or possibly drum loops or even a MIDI drum track so that your timing is kept reasonably in check.
I have a friend who plays acoustic guitar and writes his own songs. He's all over the map with his rhythm. His chord changes aren't predictable, and he may have added an extra line to verse. It's weird, but by himself it sounds pretty good. There's something about the unpredictibility that makes it interesting, and the chord choices, lyrics and vocal melody are all pretty good.
He just can't play with a drummer, a drum machine, or even a MIDI drum sequence that I tried to create just for a song. A drummer has no idea what to do with him. "Is this where that change is?....oops, guess not".
And he can't follow a relatively consistent beat. He says "it messes up my timing".
His songs are really emotional, and I'm sure he is reacting in the moment causing him to speed up or slow down slightly. And he probably forgets exactly which beat the changes are supposed to be on. He gets into it. And, as I said, it actually sounds like it's SUPPOSED to be that way when he plays by himself. Only problem is that nobody knows what to do along with him. Probably never will.
Anyway, a drummer COULD add drums after he recorded his guitar and vocals, but the drummer would probably have had to get really familiar with the quirks, and that takes time. The drummer is the clock. It's usually easier to have everyone else react to the timekeeper, than trying to get the clock to react to everything else. Not that it can't be done.

The other things that may get asked about is the quality of the recording interface, what you are running the bass and guitar through to "record direct", etc. Running through POD? Mmmmaybe. Running a guitar and bass directly to a cheap soundcard? A lot of people would say that it's probably a waste of time to try to take tracks like that, and pay for studio time. (Definitely not a waste of time to DO tracks like that, because you'll get practice and learn things).

It also could be very possible that if you manage to get a good clean bass, guitar and keyboard sound recorded, a recording studio could reamp stuff and actually make it sound better. You may also be good enough that a drummer could play the drums with no problem after the fact. Which will all also take time, though.

If you're going to hire a drummer anyway, and you know your songs well, a possibility would be to go ahead and record the bass, guitar and drums in the studio in real time, add the vocals while you are there, then take the tracks home and add keyboards and stuff? You're paying a drummer anyway to learn your song, and you're paying for him to play real-time in a studio. Why not record your guitar better while you're at it? It's the same amount of time.
Maybe provide any hired musicians with a demo of the songs beforehand, so they are familiar with them, and know what they are getting into. Seems almost a waste to hire studio time, and not record as many instruments in the same time period. (Of course, it may take a bit longer to get a sound from your guitar, etc.. But even a quick and dirty setup in a pro studio may sound worlds better than your home sound, depending).
You may just be trading the amount of time for a studio to try to figure out how to fit everything around your home-recorded, drumless compositions with recording your instruments better.

Just some thoughts. As usual, I don't claim to be the "final authority" on anything, and any misconceptions, misstatements or other factual errors on my part are my fault, and I will gladly accept constructive criticism so that I may learn more. I am merely pointing out what I think may be potential difficulties, and offering alternative ideas. :wink:

Edit: All the above didn't take into account whether it would actually be YOU that would play the drums. (Wasn't mentioned). If that is the case, then the entire scenario has changed because, obviously, you can't play the drums and guitar at the same time. Of course, if it IS you playing the drums, and you're good enough, then you already know the quirks, and may be able to quickly record. If you aren't playing drums, then the above ideas may be a consideration.

Good luck,
Kapt.Krunch

i have a four member band
iam the guitar player = lead/rythm
vocalist = vocals/rythm
drummer = yet a band member but maybe leaves the band.
bass player
keyboard = session player
i am going to order an emu1820m, infact iv ordered but just have to pay.
yet i cant afford a more expensive sound interface so thats the maximum for now.

yes i record everything with sample drum loops or at least a metronome
for the guitar and keyboard parts.
actually for now we are financialy poor well very poor i should say. so iv to stick with this plan.
i'll have to do the tracking for guitar bass and keyboards at home. as far as their sound is concerned i can get a decent tone where i record for the electric guitar and bass at least.
thanks a lot for the tips but i guess iv passed the keep in tempo point.
so whats next ?