Don't worry about walking, running, swimming, or other non-weightbearing exercise every day. You really can't do too much of that stuff unless you manage to injure yourself.
But it is important to not do strength training on the same muscle groups every day. The reason for that is that when you strength train (weightlifting, bodyweight exercises, whatever) it slightly damages your muscles - the strength and muscle gain you get afterwards comes from the "healing" process, which takes around 48-72 hours. Putting more stress on the muscles during the healing/growing process is counterproductive, prevents muscle growth, and can increase your susceptibility to injury.
You can strength train every day as long as you work different muscle groups (upper body/abs one day, lower body/back the next is how I split it up) or you can just work your whole body every other day, and do more walking or whatever on your days off.
Oh, on goal weight: assuming you're somewhere near average height for an adult female (5'4-5'7), a healthy female weight for you is in the range of something like 110-150 lbs, so aim for that range pre-T. 130-140 is healthy at almost any height. When you go on T, you'll add some weight and muscle, so if you start from a healthy female weight you'll end up at a healthy male weight without having to worry about it too much.
