Since fitness, strength, and conditioning are relative terms which mean different things to different people I don't know if your 64kg is a "fat" 64, a "solid" 64 or what.
However, based on the information you've given so far - you sound pretty thin for your height.
Let's give this a try.
Weight training M, W, F.
http://www.hypertrophy-specific.com/hst_index.html
Cardio training
Do your tri bricks 2X a week T and Th would probably be best that way you still have 2 days a week off to rest and recover. You are using metric so I'm imagining you are in europe - you do have 7 days in the week over there like we have on this side of the pond don't you?
Do your bricks like this T - swim/bike, Th- bike/run.
Try to improve no more than 10% each week. For example if you can run 1K this week - go for 1.1K next week.
Training for my first tri - I messed up badly and pushed too far, too hard, too fast and ended up back down to 170lbs with a lot of muscle loss.
Start training first for an international, olympic, or sprint distance tri. Get a couple of those under your belt, then use the same strategy to work your way up to conditioning for a 1/2 ironman...after a couple of those then you will be ready to train for a full ironman.
For more training information about bricks go here.
http://www.beginnertriathlete.com/default.asp
Don't forget to take a couple of months off from the tri training at a time and just work on
muscle growth - even the real triathletes (I'm not a real one, just someone who plays at them and finishes last...even behind the fat women) will tell you that. This is because the intense cardio you'll be doing will burn up your muscle and leave you with none to work with then.
For nutrition, try this:
Calories - 2590/day
Protein - 210g/day
Carbohydrate - 280g/day
Fat - 70g/day.
Spread this over 6-8 meals/day if you can.
Then if you aren't getting bigger and stronger with better performance after a couple of weeks, increase by approximately 250cal/day each week (2590/day this week, 2840/day next week...) until you do start getting the results you want.
If your are getting fat from it, reduce your calories by the same proportion at the same rate.
Keep your protein at 1.5-2g/lb of body weight, your carbs at 1.5-2g/lb of body weight, your fat at 0.5-1g/lb of body weight. Adjust within these paramaters to suit your individual needs.
This is the triathlete's diet - not the bodybuilders diet - but the needs are very similar...except the triathlete needs even more food to keep from wasting away.
Don't forget to convert your kilos to lbs by multipling Kilo x 2.2 before you calculate your nutritional needs.