Stow all that. The gear that you loot and earn from quests will take you to 50, and at 50, you will do missions that give you purple quality gear. Once you have done all the missions, THEN consider buying items to fill in the gaps. You do not need to go buy 5 blue quality weapons off the AH every 3 levels, its a waste of money. You should not have to buy much before 50; if you have a preferred weapon type, maybe buy a set off the vendor if you gained a few levels and have not found 2 dozen of that weapon type yet.
If you want to do something NOW to improve, buy purple bridge officers with good space and ground skills. Then buy 10 duty officers (blue and purple) that you will use in your space and ground support role slots. These will still be just as useful at 50 as they are now!
The fastest way to get dil is to make alt characters and do one foundry on each once a day. At higher levels, the "empire defense" (or explore new worlds fed side) type quests for 1400 dil take just a few (less than 10) min. At lower levels, it can take over 1/2 an hour to beat all those ships, so those may not be optimal for you yet. You can also make dil by keeping your duty officers busy, its not much, but it adds up esp on 3+ characters. Also characters are a better deal than bank space, so its a win-win. You can trade dil between your characters by putting it on the exchange at an unacceptable price, changing characters, and pulling down the offer, if you didnt know that.
I may buy some Turrets and DHCs then since I haven't come across too many as quest rewards. I'm about to jump into the Ar'kif which is like an escort so DHCs should be useful.