Southern OBS here.
The OBS role still remains not recognised by the RMT. However, you can still be a member and have representation in any disciplinary matters that might arise.
There is no personal bad feeling towards anyone of the OBS grade from any of the drivers or the conductors. It isn't an OBS's fault that the role exists, and a large majority of OBS's used to be conductors or Revenue Officers (I was the latter). New people are definitely not shunned.
If you are successful in the job you will attend a 3 day Southern induction. On this you will learn about the company and what it expects from you - you'll do bits about managing difficult situations, dealing with customers who have a disability, some basic health and safety, the drugs and alcohol policy etc... You'll also get your uniform during this time.
After that you will attend a day where you learn all about the tickets, and a day where you learn to use the ticket machine. Then there will be two days of learning the on train environment, which covers how to make announcements, how to reset the passenger alarm, how to reset the smoke alarm, reset the toilets etc .. you'll be shown the contents of the emergency cupboard, how to put the ramp down, and the contents of the driver's cab (emergency hammers, fire extinguishers, first aid kit). You'll also be taught how to make an emergency call from the driver's radio. There's probably a few other bits but they've slipped my mind just now.
The day after that, you'll meet your manager and be given a depot induction where you're shown where everything is, assigned a pigeon hole and issued with your work phone and your kit bag. You'll also be taught now to read diagrams (a sheet which outlines your work for the day). After that you'll go out with an OBS and do some shadowing, which moves on to an OBS mentor shadowing you as you start to do the role.
For me what's difficult is the pattern of earlies/lates. If you're not used to that then your first month will absolutely suck. People tell you that you get used to it, and whilst that's somewhat true, you never really do.
On the whole the job is pretty easy and laid back, but when things go tits up (which they often do) you have to be switched on and competent in what you're doing. Just last week I had a 12 carriage train that was splitting at Haywards Heath, with the front 4 going to Littlehampton and the rear 8 going to Eastbourne. The PIS was broken (the automated announcements) so no one knew where they were on the train, so I had to spend half an hour getting everyone in the right place, and then when we got to Haywards Heath they decided front 8 was for Littlehampton and rear 4 were for Eastbourne. I then had to then go back and tell people I was wrong, and then deal with the backlash of angry commuter passengers who are sick of being messed around. It was stressful as ****.
That's all I can think of just now, please ask more questions if you need to!