Hellickson would be fine as an innings eater, as an experienced pitcher who doesn't throw a lot of FBs he is a decent bet to hold up for a few years, and his changeup means he could remain effective even if his FB loses a little. But he's a #3/#4 at best, and should be paid as such. One year at $17M is ideal 2/30, 3/42, 4/52 is what I'd be offering. Discount each extra year for risk as he hits his 30s.
It's very hard to trade for #1 pitchers, there just aren't that many and teams tend to be reluctant to give them up, and at this point, trading for a #1 over 30 would be foolhardy, look at Lee and Halladay, a guy pitching well at 31-32 is still a ticking time bomb. Remember the Garcia trade - that's what happens when you get impatient. One pitcher isn't going to put them over the top.
When the Rangers traded for Hamels, it was with a contending team and a loaded farm system.
While our farm system is better, it's still a couple years from being that loaded, and we're a couple years from contending.
In the winter of 2018, if we're coming off a 85-90 win season, then you roll the dice.