K7100 --- QSFP+ connected to Port fg.1.4 (set speed to 10000) and S8 --- 4 x SFP+ connected to tg.5.4, tg.5.5 (Modul5) and tg.4.4, tg.4.5 Modul4) Is this right to connect? Or do I have to use 4 x 10G on one Modul (for example Modul4)? How to configure the LAG on both sides?
I think this should work. One thing about this design is that you are not taking advantage of the redundancy provided by bonding but it is understandable given your hardware layout on the bonded 7100. It could be a waste to consume two 40GB ports to gain the redundancy if you do not have other 10GB devices to use the spare ports.