Chris, I reckon you are either very lucky or have a very compliant set of teams.  Here in Oxfordshire, the 50+ teams in particular still think they are playing Vets (full-on) 11-a-side football, so numerous persistent occasions of contact etc and there is hardly a game in most league matches that doesn't have a number of running offences, including quite a few penalties for 4 offences - my own team actually managed to rack up 10 running offences in a single 15 min game, so I faced 2 penalties as the goalkeeper!

We have also had to deal with three very serious misconduct/violet conduct issues in the past couple of years.

We really want to introduce a worthwhile scheme that gets buy-in from the clubs and helps drive down the bad behaviour etc

I suspect it is a bit of a combination of the two John. Yes, we're definitely lucky in that the ethos behind WF is pretty much still alive down here and Teams on the whole are compliant and aren't always looking to bend rules, break them, gain advantages and so on. Although a league the taking part/fun side is still very important to the majority.
10 not walking offences in 15 mins? Wow. I don't think I give or see that many in 5 matches never mind 1. Not wanting to apportion blame here. But Surely your club has refs in it's club sessions and they are qualified? Don't they pick up on this in the sessions? What is the captain doing on the day? As I'd be shouting at my players to walk and even sub them off if they kept doing it. Personally I'd find that embarrassing for my team/club to be picked up that often. The walking or non walking has to come from the clubs/leadership and be instilled in clubs sessions so they turn up on league days and do the same. I.e. walk all the time. 

The serious misconduct/violent conduct sound really bad. Not something I would ever expect to see in WF. And I don't want to. This is where we need a totally different disciplinary process and protocols from the FA. We cannot have the same as regular football. To me something like violent conduct should be a season long ban personally. There is no room for that sort of behaviour in our game.

It makes me wonder if so many players are happy to openly break the laws now, assuming they know them, then would a FPA award stop them at all?
To me, but just my opinion, behaviour again is a club issue and should be instilled by the leadership in the club. 

Yes, 10 non-running offences in the same game was exceedingly embarrassing for me, especially as a league organiser!   I was shouting my head off from the goal to get them to stop running, but unfortunately I am not the team captain or manager - and he was one of the guilty parties.....

Sadly our own team sessions are run without referees, as we are only a small club, but generally well self-controlled with less running going on, but that could be because we play our club sessions inside a sports hall with a smaller pitch than the league, which is outside on 3G - so maybe our players feel they need to move faster to cover more ground when on the bigger league pitches!

Lol. Doesn't help if the captain is doing it! 
You also raise a really good point in the size of pitch. I'm sure the change to large pitch size is something to do with it as well.
Do you know the size of your league pitches? Specifically length?
As we change ours in club sessions and depending on numbers I will significantly reduce the length and it 100% means less walking infringements.
Reason I ask is our County FA made the pitches for the FA Cup and they were way way too long. Within spec but at the max allowed.
so in this instance there were more not walking offences committed and I'm sure it was the size of the pitch. 50m IMO is way to big and we look to an absolute max of 40m with 6 a side. Even then I think it's too long but all down to individuals. I don't know how small is small. But if possible I would suggest someone as a dedicated ref and if possible again get someone on the FA refs course. As they can then share that knowledge with everyone in the club. Before we grew we self reffed. then a player/ref and now dedicated ref. It's so so much better now. But understand it's not always easy to implement.

No it certainly doesn't help when he also constantly challenges the ref about his decisions!

Our league pitches are 46m x 24m and we use 3.66m x 1.83m goals....the sizes are partially down to us wanting to use the existing permanent lines at the leagie venue rather than having to set out loads and loads of cones on two pitches ever time we play...

Personally think the pitches are about right in size and it is our club pitches that are too small, but we can't rebuild the community centre to get mor space