26 yr old daughter & 3 yr old grandson has lived with me and husband over 3 yrs. I want custody of my grandson.

In most states the answer would be no, not without more. But you may want to discuss the situation in detail with a local family attorney.

Can i file for divorce in US, i am a US citizen, but my wife lives in Romania, and we got married in Serbia in 2003

If you meet the residency requirement in Michigan, yes. consult a local attorney to discuss your situation.

My file for divorce in florida but we live in newyork,and she is keeping my son away from me,she woundnt let me see him.advise

Your question indicates some confusion. If you have a pending case in New York she can not file in Florida.

My abusive boyfriend calls police, Crisis Services continually for even a minor disagreements

So - as a start don't take his calls. Tell him to stop calling you. Complain to the phone company about harassment. Put in a call block order if...

My ex wife informed my 4 year old sons school I am diagnosed schizofrenic. I am not at all diagnosed for it, what do i do ?

You may wish to seek a change in custody based on the activity - but you probably won't succeed. It's not enough - even though it is disgraceful...

What would be the best way to go about having my husband adopt my 2 kids ?

No. The father's consent is required.

I am looking to foster or adopt a child I know just got put into foster care.

You should talk to your local CPS or ACS office to discuss your options.

I claimed earn income credit for my daughther,she lives with me all year,can i sue my ex for deducting money from child support?

If he failed to pay as ordered or has otherwise failed to comply with it you can seek enforcement in Family Court.

Yes on the paternity - but that will not give you the right to change a name.

Can I get visitation rights if a child was put in foster care and I am only a friend of the father who HAD sole custody?

It would be highly unliikely.