The general answer to your questions is : it all depends on the agreement between band and label. I mean, labels can work in many different ways, and offer different conditions to bands.
Based on what I encountered so far, I can give some more specific answers :
zervyx wrote:
1) What happens with the sales for digital format? I mean, if the label prints the album, will the band still be allowed to sell the mp3's online?
If you're talking about selling digital downloads on Bandcamp, there are very few labels in the underground that would prevent you from doing this, so in general this is perfectly fine. If you're working with some major label, there could be such restrictions though.
On the other hand, some labels will tell you they will handle "digital distribution", which essentially means they will make your music available on iTunes, Spotify, and the like, and reap the benefits from those (possibly sharing it with you). But this does not stop you from selling digital downloads on Bandcamp or through other "direct" channels
zervyx wrote:
2) If the band gets it's share of cds, would the band be allowed to sell them online?
Same as above, in most cases that's a clear "yes".
zervyx wrote:
3) Can bands sign with more than one label? Lets say my album is released by Silent Records in Italy and then another label can release it in Canada
In general, that's not how it works. If your Italian label says it will release your CD, they intend to release it worldwide, and will do their best to distribute it as far as possible. If you would like another label to release the same album in a specific geography, you'll have to ask the Italian label if they're ok with it, but I would expect they decline. Unless it's another format, for instance if another label wants to do vinyl or cassette, then depending on your agreement with the Italian label, it could be perfectly fine.
Or they could also do a co-release with two or more labels involved, but those things are decided beforehand, and not after the album is out.