I can't decide wether i should play a rogue(10)/druid(10) or a rogue(10)/cleric(10) . . Are these good combinations for RP?

Also, i want to use a katana or a bastard sword. If i go for the katana, i want to have a dagger in my off hand.

can u guys also tell me which feats i should take and what my ability scores should be. thanks.

Druids are fantastic, but if your going the rogue route then you should definetly START with a cleric (you can switch after 1st level to a rogue). The reason is that you get two elemental bases to choose for the cleric, one in particular is HIGHLY suited to a rogue = Trickery (which allows Improved Invisibility - something you won't get with a Druid). If it were me I'd choose my second elemental base as Magic (for the stoneskin, something a Druid has).

The Trickery domain for the Cleric is a good choice, but don't forget that you wont be getting Improved Invisibility until you can cast lv. 4 cleric spells. Before that you get Invisibility Sphere at spell lv. 3 and Invisibility at spell lv. 2. For the roguish player, the Trickery domain also get a special ability called 'Divine Trickery' or somesuch that boosts your rogue abilities for a few rounds per day. This ability increases as you gain more cleric levels.

To dual-wield effectively with the weapons you mentioned you need several feats. First both of them are exotic weapons so you'll need that feat. And second you need the feats Ambidexterity, which requires 15 or higher in dexterity, and Two-weapon Fighting to avoid the dual-wielding penalties. If you have both these feats you can get the Improved Two-weapon Fighting which will allow you to make an extra attack with your off-hand weapon with a slight penalty to the attack roll. You can, if you wish, add a lv. of Ranger to get the first two feats for free but then they will only work in light armor.

The Druid don't have any real rogue skills as class skills, but you get some feats and spells that boosts at least some of these skills. Trackless step adds 4 to Hide and Move Silently while you're in a natural enviroment and the spells Camouflage, Mass Camouflage and One with the Land further boosts these skills. Note that the spells requires Shadows of Undretide.