First and foremost it looks like you live in a nice neighborhood. I like areas where there is mature tree growth, etc. These new developments made today lack so much character and many younger people are going that route. As much as all that *@*+ is overgrown, be lucky that it's there. Without it you would know all your neighbor's business and lose any amount of privacy which I find rather annoying.
Along side the driveway, I would keep the pines, they offer privacy. Trim them so they don't become overgrown and be sure to always get rid of the pin needles. If the needles add up it becomes a problem. Or, you could take out everything and, and do a screen of evergreens or abroviates (green giants, dark americans) they offer the best privacy and look good during any season. For mature trees however, remember they will cost you. 6' arbroviates will run anywhere from $80 and up. Prices jump significantly depending on the mature level of the tree.
As for the overgrown brush, vines, behind the deck that lead to the cul-de-sac, there are many steps you can go. I've landscaped many houses, the easiest and cheapest route to go is to obviously lay sod or grade the lawn and plant seed. Grass is low maintenance compared to your other options. As far as retaining walls, there are nice and serve a purpose, but to construct rock walls is NOT cheap, at least where I'm from.
If you don't want grass, you can make a large flower bed leading down to the street. Maybe a rock wall at street level, with staggered arbroviates and junipers. Large gallon Ormental grasses are nice too. Whatever you do, no red mulch, red mulch is tacky and mostly used in commercial buildings as it's the cheapest. Black mulch would not match well with your house, so natural brown would be the best route to go.
Side of Driveway: Eliminate all overgrown brush. Create bed, screen out the neighbors yard. Arbroviates provide the best screen. Staggered lookes better than straight line in my opinion, I don't know how much room you have to the property line. As for cost, if you neighbor likes to keep his yard professional and neat and likes privacy you may be able to split cose of trees with him.
Behind Deck & Back of House: Grass would be easiest and cheapest. However, cutting on a hill that steep is a %!!$!, trust me I know, especially if you get a lot of rain/water. Mulch bed with just about anything. When you clear that out it's going to be a large piece of land than you expect that's why grass is the best way to go cause it's the cheapest. The amount of mulch, soil and plants/trees you need is going to be expensive. However, it will look the best. You can do it one of two ways. You can screen at the edge of your deck and put smaller plants down towards street level, but that blocks out most of your property views. I would look into screening street level with either stone wall, fence or arbroviates, and continue up to deck with smaller plants. Junipers and groundwork are pretty and low maintenance. Ormental grasses are beautiful in late summer and they can grow to be very high. Hollys are good as are boxwoods but they require a decent amount of trimming.
Whatever the case may be, it can look absolutely gorgeous if you do it right. But remember, a lot of people think landscaping is easy and inexpensive. It's not, it's a BIG business and it will cost a lot if you want a great job done.
Best of luck.
