Yes my 3 year old did , just make sure they are wearing some shoes that can go in water with grips for the rocks

I didnt see any notices about rental and guessing since covid it would probably be stopped now anyway.

30 minutes of a very fast walk, but we've been in hurry, normally i would say it's gonna take 45 mins. Don't forget a pair of waterproof boots, as there's a lot of mud and even running water on the path and mind "last admission" time as the staff will lock the entrance in front of your faces if you will arrive even few seconds late

Most of the walk there is fine, there's one steep section with steps just before you arrive but it's fairly short. I can't remember how many steps it was but if you did need to stop half way there's a wide corner bit where you could easily pause without being in the way. At the falls themselves there's a little walk around that goes up and down with a fair few steps, but you could always ask if you could go in through the exit and bypass that to go direct to the falls instead.

It’s a really short walk of the circuit itself - probably about 15 minutes to do the whole circuit (if you are not stopping for long to look at it). The walk to the circuit is longer and quite steep in some places, however not for a long distance. It is uneven ground as you are walking through a forest, so I would suggest sturdy shoes - and they provide you with wellies at the top, but you sometimes have to wait for your size to be available.

It is a good 10-15 min walk,no level areas at all apart from the initial road leading up the hill,as such i would say not good for someone not fully able bodied.

Only with a all terrain buggy. You also may need someone with you to lift pram over some of the steep parts. Personally I would only do it again with a baby carrier. Please don't let this pit you off, it really is worth the effort.

About 2 miles. It took us about 30 minutes to walk at a steady pace - some rocks to step up / over and on a wet day it is pretty muddy too.

Yes the path through the Glen to the visitor centre is free to access, it’s a really nice walk. There’s a nice cafe and small gift shop there, payment is required to to go any further to access the waterfalls via a separate path.

All very secure. I agree, buggies not advisable, baby on your back is the only safe option in my opinion. If I were you I’d call the glen, the staff are extremely helpful.