I'm having the same experience of sticking to it better than before. I've run in the past, but not paid attention to what I was eating, and I didn't loses any weight. This time I've lost weight and my running is getting faster as a result, which in turn makes it easier to stick at the running. I've also watched the food, but not really exercised and that just makes the food so hard to stick to, because without the exercise I get bored eating within my calorie alowance all the time, whereas with some running I get to have ice cream, wine and cheese!
There's something called Shin Splints. Never had it, so I don't know anything about it but if you google it or search on this site, you'll get loads of stuff which will hopefully be helpful. I expect it's worth trying to leave it an extra day between runs and see if it makes a difference, or slow down your runs.
If you're trying to lose weight, it has to be mainly from controlling food intake. Exercise helps, but only helps, it's controlling the food that's most important. You can (well I certainly can!) always eat enough to eat back the calories you've run off, but if you're watching what you eat, the running can allow you some extra treats. I've lost 2 stone this year using My Fitness Pal, which is an app where you enter what you've eaten and work out calorie content. It's pretty tedious, although it gets easier as you use it more because you have the stuff you regularly eat entered in it, and you also get to know what sort of portions you can get away with. I also use Endomondo to track my runs, and this links into My Fitness Pal and enters the calories I've run off, so I can then have some ice cream or whatever on those days (I do try not to eat all of the calories it says I've burnt off).
Runnig with a group can be really helpful in terms of motivation and also pacing yourself. Running so you can talk to someone stops you going too fast. I've never managed to get to a regular group, but I have started going to Parkrun which is similar.
I'm a newbie, but I always take water. It's nothing to do with hydration. My mouth gets dry and I find that uncomfortable. I have a 250ml bottle, so it's virtually nothing in terms of weight to carry, and sometimes I only take a couple of sips, but I really wouldn't want to run without it.
Is a garmin more accurate than a phone then? Sorry if that's a stupid newbie question, but they're all using the same satellites surely? I am tempted to get one, but thinking of leaving it till Christmas pressie time (mainly so I can get the hubby one, whereas if I get one now, he'll get himself one now!).
Our parkrun is 4 loops, 2 big and 2 small, but all clockwise, so the "keep to the left" mantra does mean slower runners (like myself!) will run farther than the faster runners. I don't expect there's 300m in it though, which is what mine and hubby's phones fairly consistent measure the course as (5.3km).