Bonus Spells:Spellswords gain one caster level every other level after the first (respectively at 1,3,5,7,9) gaining all benefits of durations and improved spellcasting, but not any other benefits from their spellcasting class.
So let me see if I got this right. Levels in Spellsword will grant additional Spell Levels which will include additional DC, duration, and/or damage for spells. However, it will not give additional spells per day, or spells known for a sorc/bard. Is that right?
Then when taking Bard or Sorc levels do Spellsword levels count towards current Spell Casting Level as it pertains to additional spells per day or spells known?
Spellsword does not add additional spells per day or spells known.
IF we cross-over into epic and take the 21st level as a Sorcerer again, does the game mechanics recalculate and place the character effectively as a lvl 16 Sorcerer (thus choosing a bundle of new spells and gaining more pe day etc) or do they simply chose their next spell as a level 11 sorcerer (nothing really new)?
it does give you extra spell slot and higher lvl spells as a wizard..revone is proof of that as a lvl 5ftr/5wiz/4 SS i can cast lvl 5 spells.
In your example, Polak, your character would have access to 8th level spell slots (meaning that if he/she knew an 8th level spell he/she could cast it), but he/she would not have access to learning 8th level spells until he actually has 16 levels in sorcerer. At 21st level, the character would be able to learn spells as an 11th level sorcerer, even though he could cast as a 16th level sorcerer. This is why wizards typically work better as Spellswords, as they can use scrolls to learn the higher (6th, 7th, 8th) level spells to fill those higher level slots, since like the sorcerer they would not be able to learn the higher level spells at their level-up.