An excellent way to build up your network with more experienced race officials (as well as gaining knowledge and understanding) is to attend judges/race officers training and obtain accreditation. If the RYA trainining is anything like ours in Australia, its excellent value.
Do you need a bit of a rules guru to act as an arbitrator?
Well, you need a 'sound' knowledge of the rules, like when 15, 16 and 17 are likely to apply and when not, when rule 18 starts and finishes, and the right of way > limitation > room > exoneration process. This comes from a willingness to read the rules carefully.
An arbitrator also needs a good knowledge of the Arbitration Rules he or she is operating under, particularly what can and can't be decided by arbitration, and whether and at what point an ?Arbitration Penalty becomes binding.
Remember an Arbitrator can always bail out and say "this is getting too difficult for me, it should go on to a protest hearing".
Which brings me to an important point. More important than rules knowledge, IMHO, is an understanding of how to run arbitration/mediation, and an objective, non-judgemental mind-set. Unfortunately, some people who want to be Arbitrators have an authoritarian, or 'bossy' personality, and sometimes don't give parties a sense of being listened to, and sometimes rush into decisions based on insufficient information, or insufficient rules knowledge, which they express rather too forcefully.
The goal of an Arbitration (as it is for a protest hearing) is for everybody to go away feeling, if not happy, at least that they have had a fair deal.
There is another down-side to Arbitration, and that is, by avoiding full committee protest hearing, it reduces the opportunity for to build the experience of protest committee members an potential members.