The magazines for .30 and 9mm are the same, since the 9mm is a .30 cartridge 'necked-up' for 9mm. Many of these commercials came with a Nickel-plated magazine with wood bottom marked 'Germany' in very small font across the bottom.
So any mag to shoot it, and new copies of the Nickel mag are available if you want to look correct at the range
. Other than that, I'd suggest you get a spray can of Ballistol and start laying it on, including the wood. I would also take a toothbrush and scrub the grips with the Ballistol - they look pretty dry. My usual procedure is to hit every surface inside and out with the Ballistol and let it drain out while gently wiping with a microfiber cloth. What's left will eventually reduce to soft paraffin that coats everything and prevents rust while it lubes.
If you want to remove the grips, which you probably should to see if there's any rust under them and also get to the works better with the spray, first remove the magazine. Unscrew the RH grip and carefully ease it off the frame. Now unscrew the LH grip - if its not immediately loose, do not grab the lower edge and pull up on it. This usually breaks off the little rear point on the grip under the safety lever*. Gently tap on the grip from the other side of the frame which is open because you took out the mag and removed the other grip. This will dislodge it and you'll see how you have to proceed to take it off without forcing that little point - its worth about $200 because the original grip can only be original once. A replacement probably won't match the other grip, and grips usually require hand-fitting too.
Beyond this, don't experiment. Learn how to take it apart or don't try it.
*Ooops; I see yours is already broken but be careful to not do any more damage.