The easiest one is "Ben More" of which there are several. The biggest mountain in an area tends to get called Ben More. Beinn Mòr.
My own name includes the "Mòr" root. Feminine diminutive of "big" or "great". Amusingly, Google translate always translates my name as "Lord".
If you're thinking of place names in general, an obvious one from near where I live is "Garvald". Garbh Allt, or the rough burn (or stream). In Gaelic a river is abhainn but a small stream or a burn is allt.
Another one I clocked recently is a hill I'd noticed on the map labelled "Beinn na Sròine", also called "Strone Hill" in English. Once I realised the Gaelic for "nose" was "sròn" it all made sense and I had no trouble remembering it. (I suspect "na sròine" is the genitive case.)
I have a friend who is working on an edition of the entire Ordnance Survey map of Scotland with all the place names in Gaelic. I asked him what he was doing with the ones which don't have a Gaelic root and he said "translate them". But in fact most of them do. I already knew glas, garbh, gorm, buidhe, dubh, abhainn, beinn, cnoc and a lot more just from looking at maps. (A quick glance revealed a "sròn gharbh" and a "sròn tairbh". Honestly, in the Highlands every feature on the landscape has a Gaelic name.)
England is also called "Albion". (As in "perfidious Albion"!) I think I once knew where this came from but I couldn't be certain I'd remember correctly.
As to mutual intelligibility, it depends on who you ask. I could figure out what most public notices in Ireland meant from seeing the Scottish equivalent - it was mostly "these guys are really bad at spelling!" But I'm talking very simple stuff. I think some dialects of Irish are closer to Scottish Gaelic than others. Manx seems to be kind of hald way between.