It is safe contrary to what some that just have a total disdain for Dallas period. I've lived here for 40+ years and pretty much know it like the back of my hand and not afraid as a female to go to any part of Dallas. Just like anywhere you just don't do stupid things like have all of the bling on your ride and drive thru the rough parts of town w/ the windows down and stop and talk w/ the people hangin out on the streets at 2 in the morninig. DUH! I regularly go downtown for hockey games and such and it is pretty safe. I take the kids to things downtown along w/ do other business things around the area by myself. In our business we are in EVERY part of the place good and bad and never have had a problem. Like any major city there are going to be some rough areas.
If your into the young trendy areas then you will like the areas around Uptown and the new Victory area around the AAC. The basketball and hockey games are big hangouts for even the singles crowd. Greenville Ave has lots of really cool lowkey places to hangout for the weekend nights or weekend days to just chill and have a late lunch or brunch. Addison is more of the trendy area. Just about every burb in the area has some kind of festival or some sort w/ live music acts. Some pretty big names come thru for these events. Costs are really cheap and for these events are free except for maybe parking and whatever you buy to eat/drink.
Going out can be expensive or inexpensive. A lot of places have happy hour and 1/2 price appetizers so you can watch what you do and still have a great time on a budget.
I'm not to up on the rents for apartments, sorry. I do know that rents are kind of high compared to other places from what others have said moving here. I'm assuming the main reason being it is so easy to be able to afford to buy something that it's hard to rent something.
Jobs, you should have no problem. It is just one of those things like anywhere else, you have to sell yourself to the person hiring and let them know your the best for the job.
Subway? HUH?

We have DART, Dallas Area Rapid Transit. They have mostly buses and some light rail trains but that is it. They are expanding throughout the metroplex and it has gotten easier for people to commute this way w/ all of the park & rides around the metroplex.