my legs are throbbing heat

hi folks,
Recently I ran in the 'Hills to Henley' event. 30 kms, in 3 hours 10 mins.  not a fast run, but I'm happy!
the run is iconic to me, along the river torrens. I have done so much 'stuff' along that river, and I was able to re-visit some of it. the best bit was sighting the sea from 1.8 km to go.
I followed a 4 stage program - 1) 10 km at warm up aerobic pace, getting the fat burning going - up to 135 heartbeats a min. 2) 10 km heart rate up to 145, with bursts of speed on the downhill bits 3) 8 kms threshhold (going as fast as comfortable) 4) 2 kms fast as possible. It worked well.
interesting bits included a 'fast' first 20 kms, there was no 'wall', my legs wore out first and my heart 'doddled'. I took some gels for the last 10 kms and this seemed to speed me up. I need to build up my legs.
After 2 weeks, my legs are still recovering. I experienced what happens to me when I have worked too hard . I got into a cold bath, as you do for leg recovery, but started shivering, not a good sign.
I am re-assessing my goals. the adelaide marathon is a definite yes.
I'm not so sure about the trail runs. I would like to do them - 56 kms and 105 kms accross the adelaide hills.
My mag recommended a week off running, which I did. Interesting that my legs were still tired on thursday, and all but worn out during a 200 fly. On the wednesday I rode my bike into town and slightly strained a groin string ! so I hardly moved at all for the next few days and beefed up on elasticity pills and omega 3 pills. I have some fungi tea that is meant to help as well.
My mag says to do only 2 marathons a year - it must be conservative because I've met several runners who do much more than that. I am still very much a baby runner when I look at who I've met. It will be a massive task to get to their level, if at all possible. but hey ! it's very unlike me to give up on a dream ! I know why. It's complicated, involves pain, pleasure, work, and time.
I'm just back from a swim - 800 breast and 800 backstroke. my swimming fitness is picking up. I swam 400 fly the other day and am happy about that. next tuesday I will swim 800 fly - think about that. our pool will be 25 metres on the day - a short course, so I will be pushing off the wall 30 times (dive in once and touch to finish) 32 laps x 12 strokes per lap = 384 strokes, rounded up to 400. it will take around 24 minutes, will be tiring. I will be concentrating on breathing, good form and relaxing between strokes.
I've run twice this week, 5 kms monday and 10 kms wednesday. my legs are still recovering - monday was a slow run (5 kms in 32 mins), to look for niggles - no niggles. Wednesday the first lap was the slowest ever 5 kms in 37 mins, the second lap in 32 mins. The first lap was interesting because my heart rate was very low, making me think that my aerobic system had improved from the swimming I have been doing. I have run 5 kms in 26 mins so I'm a fair way off best times. given that I need to be ready for 42 kms in just over a fortnight, I will run 10 kms every other day and look for improvement. 10 km runs seem to be good for improving times. I'm tempted to do longer distances but don't want to break down muscle mass. I'll also basically stay off the plyometrics. seeing that I have only 4 weeks between runs, I'm a bit doubtful of whether or not I will be able to do them - 56 kms? 105 kms?  one step at a time and I'll keep my options open.
cheers dears.