What are my chances of being sent to group after completing airborne?

"Going to group" is not something you just do. I would start by finding out when the SF recruiter will be in your area. However, you are right that those are the MINIMUM requirements to apply to go to Special Forces Assessment and Selection. If you do choose to go to SFAS I wish you the best of luck in passing and being selected as one our few Quiet Professionals. Your days will not be short and your work will be filled with stress. Another thing to keep in mind is that going to SFAS does not block you from receiving your next assignment. If you get selected you will go back to your current unit and PCS as normal. Once the next Q Course is ready for you then you go back to Ft. Bragg. Lastly, if you are going through this just to stay in Germany then drop it now. This is a selfless choice, and the stress on your shoulders from SFAS will outweigh your desires.

I'm assuming that you're asking about going to an SF Group as a 91F MOS Soldier. I don't think odds are high (or in fact they may be zero) to go to a Group just by chance. Contact your Career Counselor and an SF Recruiter and let them know you are interested in going to an SF Group. Don't wait to let the Army reveal their next assignment to you. Furthermore, I suggest you use RallyPoint's advanced search to find other 91F in SF Groups now and ask them how they got there. Here is a SGT 91F at 10th SFG. Group luck! https://www.rallypoint.com/profiles/37656-91f-small-arms-artillery-repairer-hsc-2nd-bn

91F ... to group... You would have to call your HRC or APPD but as a SPC you might find one or two spots opened or opening. You could work at a BN or Support (CMDRs need), but only in the Arms room if it's on the MTOE even. More then likely you'll go to a post and work at a Division level shop helping your civilian counterparts repair stuff (you'll learn a lot). You are airborne, which almost means nothing as far as assignment in junior ranks. So you could be off to bragg or alaska to jump with those small arty units.
Looking at some resources there are only around 2500 total in your MOS and 484 total Army slots for 2016 at your current pay grade and most jobs are at Fort Hood, then JBLM, but a fair amount in HI... I'd ask for that.
You do have 56 jobs not slots in the SP command for SPC, so just call your HRC and ask.