Hi Salata, welcome!
Salata wrote:1) this birdy tends to bite a lot, how can i train him not to bite???
The mainstream philosophy on biting is that you let your bird bite you and don't react and your bird will eventually learn that biting doesn't achieve what it wants to achieve. I subscribe to a different philosophy which is based on figuring out what the biting triggers are and try to avoid them or distract the bird when they come. My ideas are based on this article:
http://www.parrotmag.com/home/77/396-re ... g-the-bite
Unfortunately only the first couple of paragraphs is available publicly. I've asked the author for permission to share it and am waiting for her response.
Salata wrote:2) are there any droplets or something to avoid air borne diseases? im keeping him indoors & he's constantly on my shoulder & head. should i be worried & how can i tell if he has caught any diseases? i dont want him spreading any unwanted pests!

You can go to an avian vet to get a thorough check up. The main thing to watch for is psittacosis. Generally, diseases, lice and mites that birds may get won't transfer to humans and vice versa.
Salata wrote:3) how do you trim their nails? how often? with what do you do it?
I don't trim my birds nails but if I did, I'd be inclined to file them with an emery board I think. I have let professionals do them on occasion though, however it's important to not file them down too low or they can't grip perches. The best way to look after your birds nails is natural branches (keep replacing them when the bark wears off) and cement perches.
Salata wrote:4) do i have to shower it? how do i shower it? if i place a tub of water would it shower independently or do i have to place him in the tub?
Get your bird a big water bowl so it can bath when it wants to. You can take it in the shower with you but it will probably be scared initially, you need to introduce it gradually. My two LOVE the shower and I have special perches for them in there. I take them in when I go for a shower.
Salata wrote:5) should i be washing my hands after i deal with it?
Like any pet, it's a good idea.
Salata wrote:6) is there any way at all i can train it to go toilet in its cage only, as it tends to stroll around the room and drop little surprises everywhere, even when im holding him sometimes

You can toilet train your birds, however, I choose not to because it can cause them to hold it in and can be unhealthy for them. If you do toilet train your bird, you then have a big responsibility to ensure they get enough opportunities to go. I try to keep mine off carpeted areas as much as possible and wipe it up as soon as I can when I notice them do it. I read that birds need to go at least once every 20 minutes.
Ellie