ATP,
If I were you, I would make sure to have a backup program. If you were able to do something else on the side to pay the bills than your transition would certainly be less trying. The early years as a pro aviator ( like most other worthwhile careers ) are hungry ones, both mentally and financially. You will have to burn at both ends to make it, and it just depends how hard you want to try.
You certainly can if that is what you most want.A conservative estimate is 5 years of hardship to become competitive in the market. As for the younger/older issue, that is a dual edged sword. On one hand, they may think the younger ones, although more likely to move on sooner, will accept less pay and work more hours. You can perhaps offer maturity and longevity,but at that point it will depend on the motivatonal properties of said company. Luck helps a lot!
Best of Luck in your endeavors,
Blue Skies and Tailwinds