Fish Profiles Question

I will be honest and say I don't know. The person who wrote the profiles and the programming for the Community Creator no longer owns the site, so I'm not sure how we can find out.

For fish length, I have looked at FishBase, which does usually say SL or TL, as well as the profiles on here and it is not obvious.
Stocking a fish tank is more of an art than a science; any stocking calculator by its very nature can't take every aspect into account so will only be approximate. I would be inclined not to bother whether the length is ST or TL as the tail does not add much to the size of the fish. And in those cases of long tailed variants, I would use the length of the standard fish.

With the volume, I have always assumed it is tank volume so I deduct some to allow for the decor etc and enter that volume in the CC.

Welcome.

I measured the amount I took out of the tank during the 100% water change when my tank cycled.  It's a 120 litre tank and I got 105 Litres out and estimate there was about 2 litres left in the substrate and another 3 in my external filter.

I also took the opportunity to discreetly mark 10 litre increments on the side of the tank as I was draining it which has made subsequent water changes and dosing of Prime much easier.

When I joined this forum I had a look through the fish profiles and I must say they leave a fair bit to be desired, and are incorrect in some cases. Some of the other general information was similar.

It's always best to ask on the forum before you take a plunge...

I don't fill my tanks with a hose because I don't have a hose or even a tap that I could fit one to - even the kitchen taps are not an ideal shape. I use 5L or 10L containers, because I can carry and lift them - yes it took a long time to fill the 1.5 meter tank for the axolotls, especially as I had to climb a small step ladder to do it. As well as taking substrate and decor into consideration, I also find measuring the water handy because sometimes I don't fill the tank to the maximum volume as I often use floating plants and will sometimes use a lower level of water so I can also see the floating plants, so the gap between water level and maximum volume is also taken into account. I do then mark the side of the tank in an inconspicuous place so I can check water levels when doing water changes.
 
There is a lot of information available on the internet, and it can sometimes cause more confusion because often it says different things - not wildly different, but just different enough to cause confusion to those of us who are not massively experienced. It certainly has for me.
It's worth doing some research, with SF and other sites regularly suggested here to check fish information, perhaps have a chat to the staff at your LFS, throw ideas open to the forum so that the more experienced keepers can add personal experienced and raise topics that may not have already been considered, then take it all into consideration before making a decision.
There is a lot of research material available, and a lot of information to consider, but if it leads to a tank of good water conditions and a tank of happy & healthy fish, then it's not wasted. And often some information from the experienced keepers here can lead to some handy hints that will save time in the long run.