Yes and no, Rad Alt can be a good clue but in areas with terrain it should not be relied upon. Remember that in a lot of places the terrain on the approach can be very different to that of the runway, so 2500 on the rad alt could still be 1000ft AAL.
If you struggle in the early days you could always make a note of the heights you're looking for and stick it somewhere in front of you.. it sounds a bit silly but it can help and can increase situational awareness greatly.
Also useful for tricky EO - SIDs.
Configuring will be down to your airlines SOP.
If you're doing a decelerated ILS approach then it's going to be done on height about airfield and also DME distance (maybe ATC want 160 to 4?)
it also depends on your platform altitude.
Flap 1 on the LOC is a good idea but may not be suitable in some situations.. perhaps you're miles alt with a speed constraint from ATC.
Certainly tight vectors with a tail wind behind you pushing you through your lock, you will want to be reducing speed... it all really depends on the environment and how god your vectors are, which you would learn with time.
If you have a low platform altitude (for example, 2000ft in BCN) then we'd be conf 2 before descending on the glide as per our SOP.
Or a higher platform (standard 3000ft) with a chuffing tailwind, you could take flap 2 and select speed 180, so you have the drag when you need it, then descend on the glide)
SOP here is conf2 by 2000 AAL, (SO if theshold 1800AGL = 3800 on the altimeter) and fully configured by 1000AAL.
When you select that will be again down to conditions.. tail wind, weight etc. A light 319 is going to slow down a lot quicker than a heavy 320!
A good rule of thumb a few people use for gear selection is GS + thres elev... so if you have 190kts groundspeed and 300 feet thres elev.. they reckon on taking the gear at 2200ft in standard conditions...
As for the VOR question, again depends a bit on the day IMO.
If you had "seen it happening" got yourself fully configured and at VAPP, you could quite happily descend and re-capture the profile as you would if you were high during the approach
A useful guide for FPA corrections is that 0.1° change in FPA will affect the altitude by 10 feet in the next mile.
Remember though, if 2500 is stil the tagret altitude, it's going to try and capture it which will get you even more behind for the approach. Wind it up if the missed approach altitude is below you so you don't ALT* (I assume you're after Airbus info..) but don't forget to reset the missed approach altitude later.
This is my own experience and opinion,
There are SO many variables it is impossible to give you a set solution.
You learn from experience.. once the skipper has suggested you start configuring a few times due to that 10kt tailwind you didn't notice.... you might remember next time!
I hope that helps sort of, I'm no expert and you should fly as you learn it and study it.. don't take my word for anything, ever!
Our company has some pretty good guides to a lot of this stuff, not sure if it is the same company as yours though?