BB is a great option for getting someone into the hobby - its got a fun background, great miniatures (
GW and 3rd party), is relatively cheap and most of all is great fun to play :-D
Similar to yourself I was a old school 1st edition player and only got back into it a couple of years back when a friend and I were looking for a low commitment game - I now host monthly 6-8 player gatherings at my house as loads of other friends have joined in.
We have found BB to be a great game, lots of meaningful decisions, tactical plays and different approaches - plus as the other commenter mentioned - it is quite random. This is very much a feature not a bug and the main part of the planning and decision making is all regarding your chain of risk reward - its a push your luck game with loads of ways to mitigate and play around that luck.
Also if you are interested there is a very active tournament scene worldwide - my group have only started dipping our toes into a couple of local events but have found the player base and atmosphere to be very friendly and welcoming. I am
UK based.
Regarding your questions:
Yes most boxes come with the stats of the players inside and also any new special rules that are unique to those teams and not in the main rulebook.
Also I've linked a couple of sites below, one is a simple online roster builder which makes team selection super easy and the other is a site that lists all the skills/teams/players/player aids that you could need in a nice easy to search place.
https://bbroster.com/
https://mordorbihan.fr/en/bloodbowl/skills/2020
The cards are just a way of giving you an easy reference to player stats and the like - to my mind they are pointless and expensive - but I have easy access to a printer and just print out any rosters (from the above site) which list all my players stats. The cards are certainly not necessary in any way, I have never seen them in use.
The season two box is a great deal with all the rules/tokens/pitch etc... that you will need plus obviously two full teams to play with.
Gnomes are a really fun team, they may be a little challenging to start with as the are a stunty team (a term used for the teams made up of tiny players - all of which aren't the best at BB). That said they are actually the most well rounded of the stunty teams so if you like the models give them a go, the game balance in BB is actually really good and if you are playing single time exhibition games there are tiering rules to balance teams whist league play has its own in built balancing methods.
In terms of what you will need to play them - the base gnome box comes with 14 players which you can happily make a team out of but it will be lacking a couple of quite pivotal players - the treemen!
The treemen are large single models and a gnome team can take two of them, you can play without them but I would recommend getting at least one as it really adds another dimension to the team as they are really strong and tough and can also throw the gnomes which opens up alot of play options.
In terms of models I'm actually a big fan of
GWs version and being plastic they actually aren't much more expensive than the various 3rd party option and I personally think they look alot nicer and also aren't made of resin.
GW actually make two treenment models for BB - One called a "Gnome Treeman" and the other just called a "treeman" - in game terms they are completely interchangeable and you can happily use either (I like one of each so the look nicely different). The older "Treeman" model is actually £5 cheap as it has a few less modelling options.
Other than that, as a stunty team gnomes have good access to and often the extra funds needed to hire a star player - there are a great many of these available (too many to list) and
GW sell resin models for them which are quite expensive.
Luckily there are a great many third party sculptors which make excellent alternatives to most of the star players at a much cheaper price point.
Double luckily!! the season to box comes with one of the very best star players that gnomes have access to in beautiful plastic form - Griff Oberwald! - Hes super fast, agile and tough which makes him a great player (perhaps the best) to add to a gnome team.
Hope that helps, let me know if you have any other questions and I hope you have fun with it :-)