In general, the answers to most of your questions is No!
As for Gunsmithing, that would depend upon the individual Gunsmith. In general you would need to find a Pistolsmith familiar with the design and willing to work on it. Good General Gunsmiths can be difficult to find. EAA might be willing to service them, but the cost might be prohibitive.
That is an insane price unless you are talking about a specially built Race Gun or an Engraved and Gold Inlayed Show gun, and even then that's high. I would not care how many spare magazines it came with for that price. (For that price it better come with spare magazines!) Most TA90/TZ75's go for between $250 and $400, depending upon which vintage. The Series 88 and later Tanfoglio Pistols being the most desirable. I own and operate two Series 88 TA90's (full size and compact) and they've been stellar performers, but still not worth $600 each!
Were I you, I would pass on that Pistol and go after a full sized 9mm Armscor MAP1 FS. For $350 plus FFL, plus tax, you get a brand new Tanfoglio Pistol with the original 9mm/.40 frame.http://www.armscor.com.ph/tanfoglio.htm
If the Armscor/Tanfoglio Pistols are not on the Kalifornia Approved List, a brand new 9mm EAA Witness would also be a much better deal. I would think that EAA Witnesses would be on that list by now.
Another option would be a CZ75B or CZ85 and those should be on the California Roster. You should not have to pay $600 for those, although you will probably be limited to 10 rounds.
Armscor/Tanfoglio Pistols are distributed by Centerfire Systems:http://www.centerfiresystems.com/AC-MAP1FS.aspx
If I could get $600 for my older Full Size Series 88 TA90, I would probably treat myself to a new 9mm MAP1 FS, and still have some $$ left over. Hmmmm? (In WC Fields Voice) Have I got a deal for you!
Then again, maybe not! I'm too honest and I still like my full size Series 88 TA90.