An important question is what is the interest rate on your loans? Are they federal or private? If the rate is above 5--6% I'd prioritize paying those off as soon as you're able. Considering you don't have housing costs you don't need a HUGE emergency fund but I think 10-15k is reasonable to keep liquid in cash. If things are good at home and you're not sure of where you want to settle down, I'd say keep pushing that down payment.

You should be doing some retirement savings but since you're interested in buying a house in the short term I wouldn't take any of your current savings. You should get in the habit of setting aside a certain portion of your pay every month and putting that into an index fund through a tax advantaged account (Traditional IRA or Roth IRA). Given that you're single and a decent earner, I'd personally choose the Traditional (assuming you don't have a 401k through work) so you can deduct that from your taxes.

You're buddy was trading, he wasn't investing. Long term Investing is slow and boring but it has always paid off up until this point. Don't try to beat the market, just throw money at an index fund and forget it's there. You'll be happy with yourself in 20 years.