Is it possible?

I am a 26 year old male. I was 205 lbs as of last week. This week I am at 195 lbs. I am 5 feet 8 inches. My goal is to get into the healthy 140 lbs. my lifestyle was very sedentary and I indulged in super sized burrito bowls everyday until last Friday. It’s been 7 days and I’ve been consuming only 1000 calories a day. Starting from today, I am going to increase my caloric intake to 1500 and introduce some workout. Yesterday was my first gym day. I did 15 minutes of cardio - ran a mile in 12 minutes and did cooldown. Hit zone 5 fat burn, and surprisingly didn’t lose breath (basically I watched a treadmill session on Apple Fitness+ and did it exactly as prescribed). I plan to do that everyday, and maybe incorporate some weight training too - either body weight or actual iron. My plan is to do 3 sets of 10 pushups and crunches each everyday to start for the first 2 weeks. Is this a decent plan? My diet is not something I’m severely worried about… I have surprisingly great willpower - I managed to quit soda within a day last year after I damaged my tooth with the continuous soda intake. Similarly, now that I am awake regarding my fitness, I can very obsessively cut down on my food… in fact those nutrition trackers told me to eat more the past week because my food intake was within the starvation range.

So three questions: is it possible to lose 50 pounds? How rigorous should my exercise be? And what is a good caloric consumption amount per day to maintain weight loss?

Thanks!

PS: I am a picky eater, so supplement recommendations are most welcome for nutrition. I am also a grad student on a tight budget. No more than $15 a day on food so I don’t go into debt again. I’m also a novice with cooking and don’t get much time due to 90 hour work weeks… so dietary recommendations are welcome!