GBU-10, GBU-16 and GBU-24 were planned for external carriage, but there's no word on if they'll still be integrated or when.
CBU-99/100 and CBU-105 likely will not be integrated, as those bombs aren't manufactured any more.
How many SDBs to maximum ? internaly 8 but externaly 4 on each main HPs total 16 or 24 ?
Theoretically 24, but these are the only loadouts that are currently certified for operational use:

There has not been any separation testing of SDBs from external hardpoints.
What Block planned for AIM-9X internaly ?
AIM-9X internal storage is not planned; it would require developing a special launcher, or the AIM-9X would need to be upgraded to allow for ejection launches rather than just rail launches.
1612 l FTs Block 4 ?
426 gallon (1937L) EFTs have been under development, but they might not be included in Block 4.
AGM-158C not planned right now but make sense USN have this very long stick possible externaly for Block 5 ?
JASSM was planned for external storage, but it probably won't be integrated in Block 4; many other older platforms can safely launch JASSMs (particularly JASSM-ERs) from outside the range of SAMs and fighter patrols, with those JASSMs going after targets that F-35s locate and transmit the coordinates of. It might potentially be added in Block 5.
Planned sure for Block 5 in 2024 and possible Block 4 for 2022
Block 4 is not a single software release; it's planned to have releases occurring from 2021 to 2026, with even some notable software upgrades for the F-35 occurring beginning next year (in 2019 the F-35 is being upgraded with automatic ground collision avoidance).
Block 4 and these interim software upgrades will be getting delivered through the the C2D2 (Continuous Capability Development and Delivery) plan, where software releases will be occurring every 6 months (beginning later this year), hardware is upgraded or changed every 2 years (assuming there's something to be upgraded) and core processors, etc are refreshed every 8-10 years:

You can also see the 6 month cadence in this chart (in the lower part of the "Development" section):

Previously there was going to be a Block 4 and Block 5 in the early / mid-2020s, but then that changed into Block 4A and Block 4B (with Block 5 being vaguely planned to begin in the late 2020s; like in 2028 or something), then Block 4 was split up even more into Block 4.1, Block 4.2, Block 4.3 & Block 4.4, which were going to be released roughly every 1.5 years beginning in 2021. Then last year they announced the C2D2 plan and so now it's a little bit more vague as to what specific year a feature or weapon will be integrated.