Ability to add more content
 

I'm not very familiar with Hero Lab. Since it will just include the SRD initially, will we be able to customize the races and classes with the additional data from the PHB for own private use without having to have a separate mod license?

I've played around with the Hero Lab starter set and really like how it presents characters, but I primarily run 5E games these days.

All HL game systems come with an editor tool that makes adding new "Things" possible. These new things are stored in files called .user files which are actually XML based. You will have to become familiar with the scripting language HL uses. In this way you will find more support for other game systems like Pathfinder that have had LOTS of things added to it over the years. Check my signature for help places and info. Allot the basic building blocks like "Things" and "Picks" are HL terms and not specific to a game system.

The above info is also supported by what Liz says HERE in her last statement of that post.

Yes, you will be able to add your own content. I am reworking our editor tutorials for the new system now, which will hopefully help you with specific to 5e questions.

Will I be able not only to modify the content but also the principial implementation (like was traits.str or something for the 4e version or especially the code for the character sheet printouts - like the sheet_....dat
in the 4e version)? Are the .dat files included (or at least available for
selected people) ?

Alternatively, if anything is "missing" I could provide excerpts from the code
I did (like the optional spellpoint rule from DMG and stuff like this... not sure
if this would be against the SRD though, I am only a coder, not a lawyer ^^).

If I switch from my homebrew 5e datafiles I would want to port over special
features I implemented to your version ;-)

Thanks for your work BTW and for not giving up hope on 5e and doing this
for the 5e community!

Best regards,
MagicSN