Hi, I have been suffering with this for a few weeks now leading up to a marathon, the good news being that I ran the marathon successfully. However it was a trail one, so a little softer underfoot than Berlin. My tactics were to wear supportive shoes at all times, even getting up in the night I would slip my feet into a support shoe. I also taped my foot up. This is fairly straightforward to do yourself, especially if you watch videos on YouTube. Massage and stretching exercises are also useful, and icing regularly. I was fine during and after the marathon, although it has flared up again now, a week after racing. Don't wait for the race to tape your foot, you can benefit from it now. Good luck.
I recently bought a Nathan minimalist hydration pack. It has a bladder which holds 1.5lt, and a large pocket in the back big enough to take a jacket. There are pockets down the front straps which I use for gels, tissues, ipod etc. I love the fit, I am a small woman, but it has a chest strap, and another one lower down, so it fits really snugly, and does not bounce around. I paid about £55, and couldn't be happier about choosing it.
I have a box of High 5 citrus gels, and have used them successfully this year for VLM and other shorter runs. I like the taste as they are not too sweet. I try and take them just before reaching a drinks station, but can happily take one without a drink. Works for me.
Being a member of a club is what you make of it. My club has trail/road runs 3 times a week, and a track session once a week. People are free to pick and choose if they wish to join a run. There is never any pressure to attend any meet ups. Most clubs are friendly, and I'm sure operate along the same lines. But I can highly recommend the camaraderie of training in a group, especially for longer distances. Sometimes the only thing getting me out of bed on a cold winter morning for a long run is knowing there are other people there as well, and they will encourage me all the way. I really can't think of any con's to joining a club.