Is 25 minutes/day enough?

As you said, it's your choice. Weight loss is primarily calories in<calories out. Exercise isn't necessary for it, but it certainly helps in other areas (heart health for cardio, muscle strength/retention for strength training).

Health-wise, I think it is better to work up to 45-1 hr of movement a day if you can. But certainly a consistent 25 minutes with something as hard as you are doing is very, very good! Don't burn yourself out, yeah. See how much you enjoy and just be consistent at this point, so only add more if you enjoy it.

I do have different chunks of things I do in a day, so that I can pick what sounds fun. I always do a least a bit of yoga and scheduled weights, but to make up more time I do various little workouts (often on DVDs).

I've started sprints with my fast dog, too! That doesn't take more time than walking her, but man is it more movement and heart pumping! That should work throughout most of winter here, so it'll make up for me not being as active outside, too.

For me personally, right now I'm doing the 30DS but I also go to the gym at night, and on the two days out of the week I don't go to the gym I try to get out for a walk or something because I don't feel like the 20 minutes of 30DS are enough and I like to get more stuff in. Do what feels right for you! During my other weight loss attempts I would try to cram too much in and it wore me out and I eventually stopped doing everything,

That is plenty, especially at the beginning. Time spent exercising usually isn't as important as the quality of the exercise, when you are just trying to lose a little weight & increase your general fitness.

Check out FitnessBlender on YouTube. They have 30 minute workouts for whatever you're looking for (weightloss, strength, fitness etc.)

See what the results are and then make adjustments

You seem excited and energized to do your best! Awesome!

Just pay attention to sore joints if you start doing too much.

A variety is good. I mix together two kinds of cardio almost every day.

Ride my stationary bike a while then hit the elliptical for a while if the weather is bad. On nice days ride my bike then park it at the house and run a 5k or something short like that right away.

It keeps boredom from setting in from doing the same thing for an hour or more.

Sounds like you know your goals and are slowly working toward them.

Good job!

I should only say to keep an eye on your calories to keep a healthy deficit

You are on track

If you don't see the results your after, and have the time, and energy, and not injuring yourself, then, do it. Try setting limits to the high side rather than a lower limit. make 25 minutes your minimum your committed to, but always strive for more. Another popular option when trying to increase range/ speed etc, is to ad 10% per week to time or distance or whatever your trying to improve upon.

You can lose weight without exercising. Exercising will help you get/stay healthy. These are the basic recommendations from ACSM:

150 minutes of moderate activity a week (i.e., walking); 30 minutes, 5x a week to be considered physically active.
+
150 minutes of activity, where you break a sweat a week; 30 minutes, 5x a week to achieve physical fitness.

It's pretty minimal, when you think about it.

I would add a walk in there at least 3x weekly. Listen to some music and just do it.

I'm currently doing T25. I just listen to my body. Some days the 25 min isn't enough so I add something else. Some days I can barely fit in and/or have just enough energy and will to get through the 25. If you feel like you have the energy for more, and it doesn't derail your plans or progress i.e. you do so hard one day you can't follow the program and do your T25 workout the next day, I say go for more. Especially if you're trying to lose weight or you want to eat a little more than your current calorie allowance.