I'm sorry OP, this is going to sound harsh, but why did you think that getting an older rescue dog was a good idea when you don't have funds or a clue how to train it?
Don't want to upset you, but I'm concerned that you didn't consider this.
As it stands, you have a decision to make - give up on the dog and send it back or make a commitment to the dog. The easy option is handing it back. The most rewarding option is keeping it.
I've had rescues and they're bloody hard work - very much like having a toddler with behavioural problems.
The first step is to build trust and allow the dog to have a safe place to go to when it's all a bit much. Remember that you are strangers to her and your home is strange. It's going to take time for her to settled. It took around 6 months for our first rescue to fully settle and around 1 year for our next one. This is time you need to bond and get used to each other's quirks.
With regards to pulling, I personally don't like or use Halti's. I think that they don't serve any purpose at all other than to irritate the dogs sensitive nose and make them more likely to pull, trying to get nose to paw to get it off! I've always used chest/shoulder harnesses which for me meant that I have good control of them in a heel position and then a stinky treat in front of the nose to encourage heel.
We also bought a training lead and did recalls on the lead at home, gradually increasing the distance she had to come, then doing the same while out. It on the long lead (end of lead under one foot so she doesn't leg it), with a stinky treat and a big good girl and ruffle of the ears when she gets it right. (We used to use garlic sausage but now use fish based dog treats.
Using short words like 'heel', 'sit', 'down' 'off', 'stay' are much clearer for the dog to understand and as dogs are physical rather than verbal creatures, use a hand/arm signal with each command. If she jumps, turn away and say 'off' then when she's at floor level, praise.
It's all repetition and praising good behaviour. Dogs are pack animals and essentially want to please the alpha so by removing your attention when her behaviour isn't acceptable and giving attention when it is, you're teaching her that she gets more by behaving.
Also, don't shout at her, don't do the 'getdowngetdowngetinyourbedyoubaddog' stuff as to dogs it's a jumble. Be calm, be clear and simple, be consistent and give praise when it's been earned. And give it time. It's going to take a lot of patience.
Have a look around for local training classes. Some people do the from local village halls and it's a great way of all of you bonding and learning together, even the DC should get involved with the training too. These smaller groups tend to be cheaper and are actually really good in understanding dog behaviour and will help you to love her.
Good luck!!