First time speeding ticket

Definitely hire a lawyer at least to explain what those other charges are.

Do I need an attorney present?

This is a no brainer, YES, bring an attorney.

When time served is deneid at sentencing, is there anything to be done to have it changed?

It might be unfair, but Mercer County is not known for being lenient.

Federal detainer and marshall pickup

Usually a couple of week is what he is looking at.

Will I get arrested on the spot if I turn myself in?

Take an attorney with you and make arrangements to turn yourself in and get bond set.

If the state with the warrant wants you, they'll come and get you.

You better hope the Federal Government doesn't prosecute him in Federal Court

Can you get house arrest or alternative housing for a county sentence?

It is up to the sentencing judge, but the likelihood is good because the Allegheny County Jail has limited space for female offenders

"Can an officer pull a 17 year old over and take a picture of her just cause she has expired tags?

I guess they do weird things in Oklahoma

In the state system at sentencing. However the Federal Sentencing Guidelines will count a conviction as of the date of the guilty plea or verdict.