I'm from Singapore and I could do with some advice on weights training. As this is maiden post and i do not know how much detail i need to furnish, i have prepared some of background info. If it is not irrelevant, then pls kindly move to the query section below, much appreciated and thanks so much in advance.

Routine so far:
I have been doing intense cardio circuit interval exercising (40 mins to an hour long per session) for the past seven weeks, 6 days a week usually plus 1 day rest. I skip another day in a week if I am too busy with work but to memory, that has been very rare.
Diet
I do not diet but I maintain a 3 meals a day, strict diet of oatmeal in the morning (everyday) and eat white meat and rice or porridge about 5 days a week with apples as an occasional snack. I do have this concept which I call free passes, which means about every friday or/and saturday I actually allow myself to indulge in food during dinner (but still in as much moderation as possible).
Results:
I used to weigh 84kg (185 pounds) approx and after 7 weeks of this routine, I have lost about 10kgs (22 pounds) and am currently at 74kg (163 pounds). I lost the first 7 kgs (15 pounds) after 4 weeks and the 3kgs (6.6 pounds)after another 3 weeks. At least, this is to best of memory. I am 5'4 - 5'5.
Target: Just aiming to burn fats and gain more lean muscles. Ideally speaking, hope to lose about another 7kgs (15 pounds). I would describe myself as bulky although I am not sure if that's really correct.
Query:
I am not sure about the mechanics as I am not really a gym buff. However, I assume that cardio can only do so much and after doing it for a long time, metabolism will eventually hit a standstill or may even fall. I also gather that initially, it was easy to lose fats and hence, the huge loss in weight in the first month, but, as less fats remain on the body, it might be harder to burn those away?
Hence, I figure I should take up weight lifting and will probably do so in 2-3 weeks time. I intend to focus on weight repetition.
1) Am I right about long term cardio might lead to metabolism plateauing? If so, how do i know when that happens? Should i continue with what I am doing or pick up weight training?
2) Assuming I am right, should i focus entirely on weight repetitions or still mix in with cardio once metabolism plateaus from simply cardioing?
3) I do not want to lose mass or if i have to, i would rather keep it to a minimum nor am i aiming to gain more unless aboslutely neccessary.
I hope to keep build and have lean muscles. Are they mutually exclusively or is it possible to achieve both?
Or am I wrong about ideas of how cardio eventually slows your metabolism and just stick to what I am doing now?
Sorry for the long post, and thanks everyone in advance!
