Storage will eventually be a problem if you sleeve, but the question of how soon it will be a problem will depend on which sleeves you use.
I started off using ultra-pro penny sleeves. That didn't add much to space, but the sleeves were too tall, too slippery in the hand, and not tight enough. So I upgraded to ultra-pro deck protectors, standard size. I used totally clear ones for the cards you need to see both sides of and black-backed ones for the cards you don't. As soon as I changed sleeves I went from a little space left in the box to 25% of my cards not fitting anymore.
So I built a foam board insert using some calculations to leave myself enough room. There is a picture of it here with cards through Hook Mountain Massacre in it. It really wasn't too hard. When I have time I'll share my calculations and measurements.
I also use ultra pro deck protectors (I just use clear sleeves for everything) and purchased a card storage box that I use over the original Pathfinder box -
http://www.amazon.com/BCW-Super-Monster-Row-Storage/dp/B000K41E7E/ref=pd_si m_sg_5
I use that box for both my Pathfinder cards and my Sentinels of the Multiverse cards and have plenty of room for both at the moment even with all expansions to Sentinels, so you could probably get a smaller size and still be fine just for Pathfinder.
The biggest issue I run into is that I don't have very good dividers, I have some foam dividers but not enough to put between every type of card, and with the extra room in the box sometimes things fall over, etc...
In general though I still like it over not sleeving - I think the setup in the original box is great but I was already noticing wear and tear on the cards after 1 playthrough, so if you don't mind spending some extra $$$ I personally think sleeving is the way to go.
There is no way to buy the 11 iconic minis for this game in a single pack. The best you can do is buy them individually. Paizo has them for sale. I think all the iconics are in the metal line (though some are backordered) but only a few are in the plastic line. There is also a box set of 4 of them you could use to start you collection.
Various people have also made sheets you can print out to make paper/cardboard standees. You can find them on boardgamegeek.com along with other things that might help you organize the game. Here is a link to the file section for PACG: http://boardgamegeek.com/boardgame/133038/pathfinder-adventure-card-game-ri se-of-the-runelor#files
And there is a wiki were you might be able to obtain some more background info: http://pathfinderwiki.com/wiki/Pathfinder_Wiki
Welcome to the game. It is quite enjoyable.
I should add, I've said many times before I'm tempted to buy the Rise of the Runelords Anniversary Edition publication of the adventure path this is based on.
There is also an upcoming audio dramatization of the adventure path.
I've also been tempted to pick up the actual roleplaying game. But I've only played two sessions of D&D in my life and, given how I'm usually press-ganged into being the Guild Leader in WoW, the GM in Mansions of Madness and Descent, etc, I'll probably avoid it, since GMing is kind of a pain in the butt. I wouldn't mind so much if someone else in my social group was putting in the effort to wrangle people for games, but having to arrange the game meet-up itself AND then be responsible for running all the fiddly bits of the game is just too much effort. I'll content myself with the card game, which has become mine and my wife's most favorite and longest-running activity this year outside of 20+ hour co-op video game epics, or whatever. We've completed all the content with two pairs of characters now, and are very seriously considering a third.
The audio drama interests me a bit. I grew up listening to radio plays my parents recorded on cassettes, and I've been using the BBC Lord of the Rings audio drama as a sleep-aid for years. :D Though I have built up very specific portraits of these characters based on the 3 sentences of flavor text on the back of their card. What if I dig into this Pathfinder lore and it ruins my imagination? There's some satisfaction in not turning to extended canon, or a wiki, and learning everything there is to know about a series. I know a few people really disliked the low-info on Aldern Foxglove in AP2. For me, it was just enough to spark my curiosity, and not so little that I was frustrated.
I'm in an even less familiar situation in terms of RPG. I've not played any RPG since about 1994 and even then the experience was short lived.
I'm interested in the book more for the story. Though I agree it is heartbreaking to discover a character in your mind isn't the character in the original story. But if that happens I'll just write one of them off as a clone. Anyway, the price is a bit too steep for me for now (since it would only be for reading and not for playing), though Vic does keep teasing us with little snippets.