Depending on how much you're willing to put in (money wise), the more you spend on ititial start up will probably save you more in the long run (mostly time, but not in all instances).
On the bottom end, a used single stage press for $50, a set of used lee dies for $20, a used hand priming tool ($15), a powder scooper set (not sure of cost) or cheap $15 ebay digital scale (about the same degree of accuracy) will get you going. Keep an eye on the EE for deals, as i've seen old (OLD) single stage presses that are good quality and cast iron, not aluminum, go for $15 plus shipping, and a sandblast and coat of tremclad would have them looking new. You'd probably want to add a lube pad and reloading block.
Downside = there's always more stuff to buy. Better scale, 2nd press, funnel, more dies, chamfer and debur tool, trimmer and pilots, concentricity tester, lead pot, bullet moulds, gas checks, luber/sizer.....you get the idea....there is really no top limit on what you could spend.
I would reccommend a reloading manual. Some can be found online (Lee ABCs of reloading is on google books). They might well cost as much as your used press for a print copy in good shape.
So there, for $150 bucks you've got your absolutely necessary equipment. Then you factor in the cost of compunents. This is where some initial investment, such as a lead pot, can save you money. Here's my best guess at what *I* save reloading: (my component prices are a little high as well, they're a little high here)
.308 Win Brass, once fired, bought from a cgnr, cost me 10 bucks in gas and $20 for 500 casings. Assume i get 3 reloads from each piece of brass (more like 4 or 5, some 6 or 7), that's 1500-3500 reloads for $30, or on average about 1cent per reload.
Primers: CCI 200 Large Rifle primers, 49.99/1000, or 60 bucks after tax. 6 cents per reload.
Bullet: 150 gr cast. Free wheelweights, borrowed pot, $25 mould, after 100 bullets, i'm casting for free. Cas checks 3 cents each, using borrowed luber/sizer, my die and lube, say 4 cents each for the sake of rounding.
Powder: 1lb 5744 39.99 plus tax. 7000 grains in a pound, 25 grains per reload = 17 cents.
Add in other consumeables like case lube, tumbler media, electricity, add MAYBE 3 cents per round. So:
Brass: 1 cent
Primer: 6 cents
Bullet: 4 cents
Powder 17 cents
misc: 3 cents
TOTAL: 31 cents per round
So for 20, i pay about $6.20 rounded up to the nearest dollar, or roughly 1/5 of the price of cheap factory ammo at canadian tire. $22 savings per box. I've probably loaded about 500 rounds, and saved $550 that i would have spent buying ammo, which MORE than covers double what i spent on equipment and components to load them. My time? Not worth much. You could say "I make 37 bucks an hour at work," but you don't get paid $37 an hour to sit on yer arse in front of the TV.
Mine might be a best case scenario, but it goes to show that if you're thrifty (see: spending oodles of time making something commercially available), you can save a LOT of money...like...more guns worth of money
As has been shown, you really don't need much space. A closet, some scavenged 2x4s and plywood for a bench, and a cheap $15 folding chair that can fit in the closet, and you're good to go (some stuff may make it out of the closet temporarily, like a tumbler or lead pot).
And lastly (question 1? lol), no, reloading is not difficult. It requires your uninterrupted attantion, and you can't be drunk or high on percoset or anything like that, but no, it's not hard.