As the title says, I stand to win $1,000 if I can bench press 280, and I have 6 months to do it. I'm wondering if you guys think it's possible, and I have a few other questions. Long story short, my friend bench pressed 280, got his picture on the wall of his gym. I simply said "you're so proud lol" via text, and his response was that be will give me $500 if I can do it within 6 months, and I only have to risk $25. I contemplated it for a day, then agreed because I like to challenge myself. I then booked the same bet with 3 other people, so total I stand to win $1,000 and I can only lose $50. I'm mildly athletic, play basketball sometimes, but haven't lifted since track in high school. I'm very skinny, I weigh 180 at 6 foot 2. Last week after I booked the bet I maxed out at 175, which is more than I thought I would start at. I have a few questions:

Do you think its possible?
Should I just focus on bench? In other words, if I do a few other exercises, ab work, a little leg work, would that take away from my bench recovery? It makes sense to me that if my while body had to recover or just my chest and back, it would be easier to recover if I was doing just the areas I plan to use for the bet.
Is a bench press machine good practice or should I be doing all my reps on an actual unassisted bench press? I just joined a gym and dont have a gym partner, so I've been mainly doing my reps on a sitting upright bench press machine. So I dont have to bother anyone to spot. I know I will need to learn form and stuff eventually, but I'm hoping I can get by with doing alot of the reps on the machine.

In currently starting my training doing canditos 6 week strength program, and taking whey protion shakes after I workout. If you have any other tips or advice, feel free to share. I'm excited for this bet, and although most people that I talk to say its impossible, I'm going to try and if I fail it's only $50, plus I'll be the strongest I've ever been, so its win-win!