I do feel very supported in the role. Legal Advisors will always set out the options available to the bench, and are available for guidance during deliberation. When it comes to sentencing, there are sentencing guidelines for every offence, and these give a starting point for the punishment, usually together with a range, so you can adjust your decision taking aggravating and mitigating factors into account.
You can fit in your sitting however works for you, however in my experience, sittings are dotted around the six-month period of the rota, I have never been allocated consecutive days, and multiple-day cases are rare. That said, I gave my availability (in theory) as every day. You can specify your availability, not just by day, but you can also mark your non-availability on one of the court systems, and there are enough magistrates in each court so that individual needs should be able to be accommodated. Personally, I prefer to do one sitting per fortnight, but in reality, it doesn't work quite like that.
Experienced magistrates are very welcoming and supportive, but be warned, when it comes to deliberations, you'll be asked your opinion first; this isn't to put you on the spot or under pressure, but to ensure that your views aren't affected by those with more experience. You have an equal voice, and if the two wingers disagree with the PJ, then that will be discussed, but ultimately, majority rules.
Diversity is tricky for me to comment on, as I live in an area with very little. However, as I think I mentioned earlier, there are networks for BAME magistrates, also LGBT+ and young magistrates. I have sat with a colleague who is registered blind, he is provided with a taxi to and from court. Older building might have accessibility issues, but in theory, disability should not be a bar to becoming a magistrate.
I have done jury service twice and spent most of that time waiting. And then waiting some more, not just waiting to be allocated a case, but then waiting while legal arguments, which are not suitable for jurors to hear, are discussed. As a magistrate, there is definitely some waiting around; often to do with getting the accused transport to court from the local prison, but generally, if a case stops for reports, or whatever, you can work other cases while that work is going on.