Exercise and training, which direction might be best?

Here is a video from about two months ago of some things I was working on. The video shows my limitations but I don't think it shows my potential. Anyway, I'm always trying to get stronger and be more functional and just reach for the ability that I know I have. I will always be disabled yes but I know I can be much better. I'm still struggling to figure out exactly what I need to do, the best simple but effective exercise routines that will increase my ability. So in the mean time I do what I can. A few weeks ago someone told me to lookup the angry quad on youtube, if you are interested in a serious workout plan for quads that will bring results I highly recommend looking him up. One of his focuses is doing core work from the floor. He has been a great motivation to me.

Anyway, here's where I'm at: I'm doing my exercise routines regularly. I have a friend that says he will help me with my workouts maybe once a week since we both work. I think a friend willing to help may allow me to work on a few things that I otherwise wouldn't be able to. But what things should I focus on is what I'm trying to figure out. Maybe practicing standing up from my chair? Maybe practicing situps from the floor? The time he helps me I want to find a few key routines to practice that will make a great impact on my abilities. Any thoughts? I have an incomplete sci and reliant on a chair and my left side is weaker but I know I can do almost anything. The first try may not be too good but with dedicated time and training I know improvements will happen.

I'm also trying to figure out what equipment I can add to my routine that might help. I have 3 things I'm thinking of, I think they will all help but trying to figure out which to add first.

1. The human trainer suspension trainer, here's a video:  I think straps like this attached securely can offer a lot of training options. Maybe I can do it cheaper with someone to install ceiling mounts and just use store bought straps? But I really like this one better than any others I've seen out there. One reason being the different levels you can attach your handles or attachments to instead of having to readjust when needed.

2. Homemade parallel bars to practice walking safely without my gait trainer and maybe practice squats safely. I think this kind of design looks safe and hopefully not too expensive: theleanberets.com/wp-content/uploads/2013/05/BARS-PVC-HIGH-DISPLAY-12.jpg
 
3. I use a gait trainer, the up n free from easy walking. It has a bicycle seat and waist strap and lets me practice walking safely with little assistance. Of course a regular walker would be better but I wouldn't put in as much work day in and day out with relying on someone else to always walk with me every step just to be safe. But, I'm wondering if I put these arm attachments on a regular walker to strap my arms securely if I could walk safer with a regular walker and be on the full weight of my feet / legs more? www.walmart.com/ip/Medline-Platform-Walker-Attachment/7983663

Those are my 3 thoughts at the moment. For me practicing walking is great and a must but I also try to be careful of putting all my focus on walking and neglecting full body improvements like core and arm and shoulder and even leg movements that are not practiced with just stepping forward movements. So out of the 3, thoughts / ideas / priority / suggestions please?

What I'm also trying to gain is a understanding of is how the body and limbs move and figure out which movements and exercises are more important than others. Being in a wheelchair I have forgotten how the body naturally works. Sometimes I watch able bodied people do simple things without thinking and try to figure out what muscles need to be strengthened and practiced to do those things. Arms, core, legs, it's simple enough to say work those areas, but with limited time and there being 500 different ways to workout I hope to find a few routines that I can go hard at and know I'm doing the right thing for my desired results instead of just doing something day in and day out and hoping it's a good routine. 

I appreciate all the help and knowledge shared. Always keep trying guys.

Ian