You have tried several batteries. That they don't work shouldn't be dependent on the charging port connector. Have you tried using an external charger to charge one of these batteries up? It might not be worth replacing the charging port if you can get by with an external charger.
Have you tried the touchscreen test facility by doing *#0*# from the dialer screen. What were you doing before the touchscreen failed: raining, cold, dropped ? I have come across a few where the internal cable was broken but just managed to stay squeezed into position to make contact; any slight jolt would dislodge it. In the absence of other info, I'm guessing a damaged cable: in that case you'd need to replace the entire glass/lcd/TSP.
The ear speaker is bonded to the chassis. You need to do the whole teardown to get to it. Check that the speaker really is broken: it may just be a bad contact to the motherboard. It might be easier just to buy a reconditioned chassis for a few pounds, which will include the speaker, as it seems to be quite difficult to get the speaker out when you get to it.
You can't get 901F-specific screens/digitisers anywhere. However, I've found that 900x ones work perfectly well in a 901. It seems that there are some incompatibilities between phones and screens, but this is not correlated with the 901/900 distinction. Best idea is to pull a screen from a 900 phone and transplant it and see if it works.
Don't worry about the punctuation: G901F and SM-G901F mean the same thing. Whether the product actually does fit however, is another matter. I have purchased several chinese (900) digitisers and pulled displays from several 900 phones and they have all worked with all the 901 phones I had here at the time.
This is an odd one. Several people have reported that a 901 screen in a 900 phone and vice versa, wil cause a boot loop. However, I've found this not to be the case, both with genuine screens pulled from phones and with cheap chinese ones. It seems that at some point, software on phones and hardware on screens 'met in the middle'. Sorry, I couldn't be more specific