The class builder cares only about the maximum divine or arcane spell level the class is capable of wielding. Just as you pay immediately for abilities you can't use until gaining higher levels, you don't pay extra for high-level abilities you get to use immediately. 

Bonus spells are for spells outside a spell-caster's normal progression, innate or at-will spells, or "one-off" spells available to a non-spell caster.

Does that help?

I figure the worksheets will be of use only to those with the book, and since I don't want to give away all my secrets for free, I'll create a PDF with all the completed worksheets for reference and make that available to existing customers. 

Addenda can be added here, though - there are a few items that probably should have been included in the book that became apparent only after publishing. Plus, putting those items on the site gives people a chance to comment and add their own.

In the meantime, feel free to share any work you're comfortable sharing.  ?

On the plus side, I've been thinking about using this forum for not only posting the worksheets, but also addenda to the Class Builder book (new special abilities and restrictions, guidelines for creating your own, and potentially new classes).

Worksheets will be bundled as a PDF and sent to existing customers via DTRPG.

I'm wrapping up a fairly intensive project at work in early April, after which I can return to this commitment - look for better progress from my lazy ass next month.

The biggest challenge with the OSE Advanced classes is how to translate their abilities - you still gotta eyeball 'em in some cases. For example, the OSE Advanced barbarian gets "Agile Fighting," while the Class Builder barbarian gets "Dodge." Obviously, both are meant to reflect the Conan-archetype by man-handling the character's AC adjustment.

The OSE version is a flat bonus that maxes out at +4 AC at 10th level. I could translate this to the Class Builder's Defensive Bonus ability, which costs 100 XP per point of AC. Normally, that's 400XP. However, Defensive Bonus stipulates "predefined circumstances or against specific foes," and since Agile Fighting is "always on," I'd consider doubling that to 800XP.* 

The Class Builder's barbarian improves their DEX adjustment to AC based on the type of armour they're wearing (x3 for no armour or x2 if wearing chain). This isn't a flat AC bonus- it varies by the character's DEX. In fact, it only helps is the PC has a DEX of 13+. So here's how I eyeballed it: Start with Defensive Bonus (100XP / point of AC), and figure the average AC bonus would be +2 (200XP); it's "always on," so double it (400XP), but not every barbarian character can take advantage of it, so halve it (200XP). 

How an ability manifests affects how well it translates to a Class Builder ability, so as a referee, you may have to adjust up or down. Yet, as an interesting side note, you'll see that both the Class Builder and OSE Advanced versions of the barbarian have a base XP of 2,500. ? 

* Fun fact: When adjusting special ability XP costs, halve if use if further restricted or double if an existing restriction is ignored. This isn't written down anywhere, but it's a good rule of thumb.  

Basic Abilities

• Prime Requisite: 1
• Hit Dice: d6
• Armour: Restricted
• Shield: No
• Weapons: Restricted
• Languages: Alignment, Common, +6 additional
• Combat Progression: As cleric/thief
• Saving Throws: As thief

Special Abilities

• Immunity: song-based magical effects, beguiling powers of fey
• Skill, innate: Lore   
• Spell Casting: Divine spells (max spell level = 4)
• Spells, bonus: Enchantment ~ charm person (lvl 1), animal friendship (lvl 1), charm monster (lvl 4)
• Using Magic Items: As cleric

OSE Bard songs affect persons at 1st level, animals at 4th level, and monsters at 7th level. I've taken the easy route and equated these to existing spells (Charm Person, Animal Friendship, and Charm Monster), which comes out to 6 bonus spell levels, thus 600XP for a spell caster.  

Restrictions

• Requirements: DEX, INT
• Max Level: 14
• Stronghold Level: 11
• Size: n/a
• Equipment: Instrument or holy symbol (?)
• Pledge: Deity disfavour
• Weakness: n/a

Assuming I got all the bits, the Class Builder gives me a base XP of 2,000 and the level progression looks to be that of a fighter. 

Let me know if this helps answer your question. 

Cheers!