There are no stupid questions on here (although it is sometimes easier to post separate threads rather than lots in one thread
)
1. Adding compost will be pretty expensive. If you don't have access to manure I wouldn't bother this year. Compost and manure are soil conditioners - they improve the structure of the soil. Once you know from experience what sort of soil you've got, you can plan better for next winter / year.
You could add general purpose fertiliser such as growmore or fish blood and bone if you want to improve the nutrient levels.
2. Some flowers attract beneficial / pollinating insects. Some are said to have a beneficial effect called companion planting - deter pests by confusing them (though the evidence for this is not consistent). Some flowers are just nice!
3. Many weeds are not suitable for composting in a domestic heap because it doesn't get warm enough. Do not compost perennial (come back every year) weeds such as nettle roots, docks, dandelions, couch grass, ground elder, marestail, bindweed. Also do not compost flowering weeds.
I use a plastic bin which looks like a dalek. Others use a heap in the corner. Others make a wooden bin which is about 1m square from recycled pallets and a piece of carpet on the top.
The most important thing is to have a mix of green (including kitchen veg peelings) and brown material (slightly woodier, or paper / shredded cardboard) so that it doesn't go all slimy. Avoid dairy, meat or cooked products.
4. Raised beds are ideal where there are drainage issues or where the bed needs to be raised for accessibility purposes. Other than that, my personal view is that they are an unnecessary fad. They do encourage you not to walk on the bed itself, but you can achieve that without the borders. Also, until you've grown on the plot for a year you won't know where you want your beds definitely to be.