If you had b27 firmware you gained pretty much nothing by updating to b30. It will land a little slower and take off seems to occur at two power stages now. The first a little and the second a lot more. It also seems to me the aircraft is a little less agile with the b30. For the most part b30 was written to "de-tune" the H as many newbies bought one and found it was more than they could handle.
If you put 6300ma into a battery it had to have been pretty much dead flat and probably would not accept a charge. Yuneec ships their batteries at a voltage level higher than a normal storage level. If you charge your batteries at a 6A rate you'll be fine despite the 5400ma label. You can probably go as high as a 6.3A rate. Many do.
The two short downward facing tubes exiting the bottom of the aircraft are antenna tubes, not antennas. The 2.4GHz antennas (two in quantity) still exit the bottom of the aircraft and now run inside two hollow plastic tubes. The original version of the H Standard employed just the two wire antennas exiting the bottom of the fuselage without anything protecting them. More often than not one of them would have been run under one of the warning labels. Those that understand 2.4GHz RC knew that antenna needed to be freed from the label for the best propagation. The two exit tubes were a feature originally found on the Typhoon H Pro, as was the three antenna transmitter. The H Standard came with a two antenna transmitter. If you want dipole antennas you'll need to buy a kit and install them, or have them installed. They really don't make much of a difference. I have an H with them and one without them.
Yes, you can watch the videos that are on the SD card on the ST-16 but the card will need to be inserted into the SD-16 to do so. I suggest you transfer those video and test files to a new folder that you'll make in the ST-16 to assure you retain them. Save that SD card. Set it aside and use it only for firmware upgrades. Buy a 32gig to 64gig card for your video and photo recording. Make sure the card has a write speed of at least 95Mb/s.
Hopefully you will not be depending on the ST-16 to review your videos. The video stored in the ST-16 is degraded to 720P and over written as the temporary folder they are stored in become full. Read the documentation and you may find in it the number of videos and photos that can be stored in the temporary folder is limited in quantity. The SD card will have the good video and if you play it in the ST-16 you will not generate any better than 720P resolution. You must play the card files in another device if you want to view 1080 or 4k video.
Stop worrying yourself into a panic. The H is a great machine and treats those people well that take the time to read instructions, review videos, and follow directions. Get the calibrations done, charge the batteries, go to a wide open space, and fly it around in Angle mode. Learn the controls and ST-16 screen navigation. Learn where the voltage, GPS, and distance indicators and and get used to looking at them periodically. Don't fly down to a low battery warning, land at or before 14.4v at the aircraft battery. They'll last longer that way. You don't have to do everything possible to do on the first flight. Those that try that are the ones that run into things or drive it into the ground. Understand the H does not have any "anti crash into the ground" protection devices. If you elect to fly fast and low with the gear up you most certainly can rip the camera off if you go too low. Aside from that warning there's not much to worry about. If you've flown camera rigs before you'll find the H to be more agile than most. Yes, it can twitch a little when departing a hover but you'll never see the results of that in the video. The gimbal is too good and counters that just fine. If you are inexperienced, take things slow and stay close until you have your act together. Now go fly and have fun. Remember, no hurry, no worry.