I would take your paper samples to the paint stole and have them do a color match to the grey areas of the designs - then choose the one you prefer, or both.

I would love to share one of my favourite pieces from a hallway collection, but I also adore the accent/feature wall idea and the image that Dytecture shared. I think a better light fitting is needed too, to make it lighter, brighter and more current. Do you have glass in your front door?

Wall stickers are super easy to remove, and leave no marks if done slowly - wall paper is a little more involved.

As I said before keeping clutter under control is the key, get lots of storage ,you said cost is I s an issue. Look at IKEA they have solutions for wall units that you can get in different colours and that in itself will brighten the place. You would benefit from a buffet next to the kitchen /dining area or a large wall unit with lots of shelfs and drawers, coffee table with storage drawers , storage unit with baskets for kids toys and school stuff, once you have this under control start adding rugs if think you still need it. By the look of it you have small kids get them to put things in appropriate place and get some funky coat hangers in the entrance so they can hang hats and bags etc.