Which Mast is my MiFi connected to ?

If your connection isn't that good you can use something to block the signal and work it out using siteviewer.ie

A metal biscuit tin works for me when the tin is in front of the Mifi and in line with the mast I get no signal, take the tin away and the signal comes back.

You mentioned somewhere getting a connection from a mast 25 miles away across Galway bay and that sounds possible as for some reason over water you can get a signal from further away, guess it must bounce or be reflected in someway.

I don't know how you can read the connection information off a MiFi device, but it can be done with an older dongle and some software. If you can get hold of something like an old E220 dongle for testing I'll look up the software.