Do reserve units provide initial issue to prior service?

Yes, you will receive another basic issue. When you get that issue is another discussion.

Yes, you will get a full basic issue.
In my experience, the best and most expedient way to accomplish this is to go to CIF on an appointment. It is a pain to travel, but it is worth it to not have to wait months for the system to get around to mailing you enough piecemeal items to cobble together what you need to be in uniform to train. If your unit is on it's game, they should give you orders and reimburse the travel through DTS.

You should get a supplemental issue. Stay on your S4, because all the paperwork is a lot of work. If you have an AGR supply SGT, they should know how to do it. It is a pain in the ass, so they will avoid it at all costs. Keep at it, and you will get what you need. TA-50 will be issued with CiFsm. They will do the paperwork, and your gear will be shipped to your unit. You will then sign for it and keep it until you get out.

I know everyone I know that has had a break in service has been given a full initial issue when coming back to the Guard/Reserves.

I wasnt even given a full issue. I was given only two acus, pack of socks, and pack of shirts. that was it along side terrible welco boots.

Another Update: I ended up finally getting my pay sorted out (although I need to refile for direct deposit) but that is step 1 of many. I am using my chain of command (1st line supervisor to my PLT SGT) so that is going. I assume since I am getting paid I am on some sort of books somewhere Army wide. That could mean I can get uniforms and things ordered. This will be my 3rd battle assembly and still going in normal clothes.

I wanted to say thank you for all the responses, it's been about a month since I asked the question and about 4 months since I have been going to battle assembly on the weekends I need to. I have a paperwork issue still, my unit is looking into it that is causing me not to show up on the battle roster which in turn effects pay (then obviously controls when I would be able to get issued items) as well as another initial issue and my bonus. It's a little un-motivating to say the least. I am using my chain of command and trying to get some of the issues resolved, hopefully soon.

You should get an initial issue but I can guarantee it will take forever. Plus you probably won't receive everything. This could take years.

You will get your clothing bag issued to you...but it may be in parts. Class A in one order, duty uniforms in another, and field gear in a separate order.
It may be possible for your unit to go to clothing and sales with a purchase order to get uniforms. One potential roadblock is the pending change of uniform pattern. The Reserve is not expected to be able to order the new pattern until end of 2015, or beginning of Fiscal 2016. The old pattern has been phased out and no longer produced. If you have odd sizes, it may be hard to find uniforms in the old pattern.

But yes, you will get something

You should get issued all that stuff when entering the reserves. The only problem is they have to order it so buying at least 1 uniform and boots before your first drill would be a good idea. That is what I did. For class A's though I think you have to buy them your self since your Ikes are no longer in use.I would check with the supply NCO first on that.