About rolling the fireball DC: That´s simple.
The designers wanted ONE roll for everything. So you might set fixed saves like AC and roll for the DC... but that´s no real difference.
It's a paladin, so don't forget the stat boosters for Cha (you might drop the vest of resistance and concentrate on high charisma for saves) and max turning a bit. Extra Turning and Divine Shield/Vigor/Might might be interesting too (perhaps 2 levels fighter or think about the prestige paladin...
The feat index doesn't have much more ... Adaptable Flanker too from PHB 2.
Feat Index
Only thing coming to my mind is a Kalamar feat called "Hammer and Fist".
Agreeing with Arkhandus, a full multiclass feat in the style of Daring Outlaw or Swift Hunter would be much too strong for eldritch blast... especially since there's no real defense against it.
I'd allow a feat like Practised Spellcaster/Manifester though to raise the eldritch blast output a...
Agreeing with StreamofSky. 2 levels barbarian are great for charging and spring attacking rogues. Uncanny Dodge Synergy is great and you make up for the loss of sneak attack damage by taking a twohanded weapon, Power Attack and Cleave. Reach weapons are nice for this build too.
If you go...
Critical Strike from the SpC is well as nice. Swift action spell for more sneak attack goodness. (Dunno if it's for clerics too)
Telling Blow (PHB2) and weapons with high crit range would be another beef up.
Psychic warrior: Armor, Force screen, Thicken Skin, Vigor (not AC, but hitpoints) and that Deflection power. AC higher than 25 at level 3, assuming enough Wisdom for power points and time to prepare.
That class is great for recurring BBEGs, not for players (except the abovementioned one level dips).
It's meant to take a NPC with 4 or 5 levels more than the players and play havoc without killing players. Every encounter you use totally different tactics and abilities. And get away if you...
Nice, I just wanted to open a thread about rogues in 3.5 and their weak sneak attack.
I have another problem though. The scout. Since we had that class around, noone took the rogue class anymore. Especially with Improved Skirmish and perhaps Swift Hunter, nearly almost always the scout dishes...