Tales of Symphonia GRADE And EXP question (google is not my friend for this game)

I googled everywhere for quick ways to get grade and bonus experience and cant seem to find much, I guess this game wasn’t very popular.

I know that you have a bonus for finishing a battle under 15 seconds but im not even sure how much of a bonus I get for that, it seems to vary.. Does anyone know all the different ways I can get Grade, im still pretty early into the game, just going into Palmacosta ranch to save chocolate and I want some level 4 ex spheres. the fastest I found so far at this point is to just hack and slash using only attack . .. I really cant find nothing really about early grade farming.. if someone could even maybe help out with that, id be greatful. THANKS EVERYONE!!!!!!

Things im looking to find out are
1. How much grade do I get for finishing a battle in under 15 seconds???
2. Are there other tactics I can use in battle to gain more grade bonuses?? the only one I know of is the 15 second defeat.
3. Will I get more experience if I only use 1 player in my party?? Like in final fantasy IX(9), if I kill every everyone will I get triple or quadriple the amount of ap and exp? it varies so much I cant tell if it works or not.
Main reason im asking is because one battle ill get 1.50 grade and 100 exp and then the next ill use the same tactic with the same outcome and receive under 1.0 grade an only around 80 experience.

———- Post added at 02:51 AM ———- Previous post was at 02:47 AM ———-

wow and to my surprise almost directly after posting these questions I came across a grade guide. here it is if anyone else is or ever was curious

The system grades how well you fought after each battle. Most battles tend
to range between -2.00 and 2.00 grade points, but the total possible range
is bigger (not sure how big… -15.00~15.00?). The grade increase option in
the Grade Shop makes the max +20.

You can use your grade points to purchase stuff sometimes. It also effects
which things you get to keep when you go into Clear File (playing the game
after beating it).

Details of grade acquisition:

Defend against enemy attack +0.01 (each time)
Use defensive skill against enemy attack +0.02
Get 5+ combo +0.02 (20hit=0.02*4= +0.08, etc)
Enemy killed w/ combo +0.04 (combo number * 0.04)
HP is full at battle end +0.25 (per person)
TP is full at battle end +0.25 (per person)
Do a successful U-Attack +0.50
Battle ends within 15sec +0.50
Battle ends within 5sec +?
Take damage -0.01 (each time)
Use an item -0.05 (each time)
Attack w/ element enemy is strong against -0.05 (each time)
Enemy gets an 8+ combo -0.10 (16 hits is -0.20, etc)
Character dies -0.50 (each time)
Character you control dies -1.00 (each time)
Dead character at end of battle -0.50 (per person)
Status effect at end of battle -0.50 (per person)

Your grade is also decreased if you’re at a very, very high level compared
to the enemy. Nonetheless, it’s still efficiant to hunt for Grade near
Iselia at the end of the game because of the bonuses you get for speed and
full HP/TP.

[Uber-Thanks: Majestic Fantasian]