[Marico]

After a few flights my Revolution has some problems with  GPS detection (ublox, m8N). GPS serial speed (hardware tab in GCS) is set to 115200, system Settings->GPSSettings->UbxAutoConfig is set to AutoBaudAndConfigure. What is the difference between AutoBaud and AutoBaudAndConfigure and AutoBaudConfigureAndStore?
First thought was there is a connection/wiring problem (got loose after few flights) but no. It just won't always detect it after connecting the battery as it was before. When I change speed in Hardware tab sometimes detect it but after such change system refuse to arm and need restart. And after restart problem occur again. It just need a couple of times reconnecting flight battery to detect GPS... What's going on?

[TheOtherCliff]

After a few flights my Revolution has some problems with  GPS detection (ublox, m8N). GPS serial speed (hardware tab in GCS) is set to 115200

I've never used 115200.  I use 57600.  You might try that.

system Settings->GPSSettings->UbxAutoConfig is set to AutoBaudAndConfigure. What is the difference between AutoBaud and AutoBaudAndConfigure and AutoBaudConfigureAndStore?

Previously you had to configure the GPS itself to have a certain baud rate and to send a certain set of messages.  LibrePilot does that for you automatically.

Autobaud only detects the GPS baud rate, and changes it to whatever you have configured.
AutoBaudAndConfigure adds configuring it to send the correct set of message types.  This is the default and is recommended.  No matter how the GPS is configured, it will be temporarily (till power off) changed to the correct values.
AutoBaudConfigureAndStore also stores the correct configuration permanently.  This was useful for a few historical reasons.  Today it is mainly useful if your GPS looses power (or otherwise reboots) and then power comes back, while the FC has power the whole time, in the middle of a flight.  It is also useful in that it removes extra configured messages as there is no temporary settings reset, only permanently clear them and reboot.  AutoBaudAndConfigure does not remove any extra messages.

Any change to GpsSettings or GPS baud rate will re-run whatever your autoconfig option is set to.

Be aware that all 4 wires are needed for the GPS to work correctly.

If you catch it failing, you can look at GpsPositionSensor: AutoConfigStatus, BaudRate, and SensorType to see if it is trying or has given up.  If it is trying, you can unplug and plug the GPS to see if that fixes it.  If that fixes it, it sounds like bad cable, connector, or GPS.

Vibration is a bad thing over the long term.  You MUST carefully balance your props, or your connectors and wires will go bad quickly.  I carefully run one motor up at a time holding the quad in hand, and using Output->TestOutputs to check for vibration.  This is dangerous, so you do it at your own risk.  I really recommend getting used to it with props off and maybe wearing a coat and gloves for protection.  Set all Output sliders all the way to the left.  Enable TestOutputs (read the warning).  Slowly move one slider (observe that you know which motor with NW, NE, SE, SW) a little to the right till that motor starts.  Hold the quad tightly and safely.  Increase power.  For up to 500 sized quads you should be able to hold it at full power on one motor.  Try all motors, one at a time.  It's usually obvious if there is a bad vibration problem.