To 1) See manual, ch 38.1:
Line In 3-4, front
• as AD, but:
• Additional Gain stage: 0 up to +12 dB
• Maximum input level, Lo Gain, Gain 0 dB: Line +19 dBu, Inst +13 dBu
• Maximum input level, -10 dBV, Gain 12 dB: Line -7.5 dBu, Inst -13.5 dBu
• Input impedance Inst: 470 kOhm
• Input Gain Inst: +6 dB
• Input mode: Line balanced (TRS), Inst unbalanced (TS)
• CLIP LED: 0 dBFS
• SIG LED: -60 dBFS
To 2) see manuals ... i.e. Babyface Pro FS, UFX II, UFX+ have 1 MOhm. 802 has 800 kOhm.
I would recommend you to choose either UFX II or UFX+ because of the later design, even better quality and more advanced features.
Both interfaces dropped in price, most significant the UFX+ which is now a real bargain. Initially the UFX+ costed €2699 now you can get it for €2139 which is €560 less (-21%).
Compared to the UFX II which costs €1879 you only have to pay €260 (+14%) to get MADI and by this USB3 and Thunderbolt.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13