PzD wrote:We'll move to a bigger rehearsal room (36 square meters, aside of my garage) as soon as I've finished the phonic insulation, and thats why I want to replace the old speakers (cheap ones, bought in the 90'), with more flexibility and power (for personal use, in private events), even if the PA amp cannot handle it right now ... I just want to go step-by-step ... I've a friend to hepl me for these projects, having lots of tools and experience in woodworking ... I planned to build a pair of OmniTop12
Since your friend has the tools and experience, you should consider DR250s instead of OT12s.
PzD wrote:future are subs (near future), 16 inputs mixing table and recording equipment, appropriate Power Amp ... But I take all advices on mixing table and power amp stuff
That's going to be the expensive sticking point. Your Mackie will "work" for a set of tops, but there's no way to expand on it to use it with subs. So, when you're "ready" to add subs, you'll also need your new mixer, power amp(s), active crossover, EQs, limiters, a lot more cables, more mics, and other miscellaneous expenses. In other words, it won't be a matter of buying one piece of the new gear at a time and adding it to your Mackie setup; you'll pretty much need it all at once.
To choose an appropriate mixer, you must first determine how many channels you'll need in order to run everything into the board; 1 channel per vocalist, 1 channel per instrument, and 1 channel for each drum mic. The drums are the tricky part of the equation, because although you may only use a few mics on the drums at first, that number will grow as the drummer buys more mics, until his entire kit is properly mic'd. Example: 3 vocal mics, 1 guitar, 1 bass guitar, 1 keyboard, 3 drum mics ... that's 9 channels. But then, what happens if the guitarist needs to play acoustic guitar for some songs, the keyboardist adds another keyboard, and the drummer buys mics for each drum plus two overheads for cymbals (that's 7 mics for a 5-piece kit). You may not be able to foresee that at this point in time, but once you have a good, full PA up and running, those types of things will happen, quickly. Even the 16 channel mixer in your plans may quickly become inadequate. It's better to be prepared for that in your planning and purchase stages rather than having to say "sorry, mates, we're stuck with our limitations due to poor foresight in the planning stage".
For your planned setup of a pair of tops and a pair of subs, and given your budget, a Crown XTi 2000 may be a good solution, especially if one of you already has a laptop that you can use with it. It can supply adequate power, crossovers, limiters, and EQ, all in one tidy package.
Although this may all seem like a big financial mountain being piled in front of you, it's really not. Yes, it will cost you some cash up-front, but there will be serious potential benefits on the other side. Once you have a great sounding, full pro PA, your band will sound 100% better, immediately, so you'll have greater potential to land more gigs, and bigger gigs, paying more money. Your investment can pay for itself quickly if you put forth the effort.