1. How do you get the paintings for the museums 2. How do you get more..

1) You must win a contest at master rank.

2) Defeat the Pokemon league, defeat all 70 trainers, complete your Pokedex, win all contests at master rank and defeat the battle tower.

3) Not sure...

To get the paintings for the museum you must win a Master Rank Contest with at least five hearts of appeal on the final results screen.

To change the colour of your card you must obtain all five paintings, defeat the Pok�mon League, obtain all Gold Symbols at the Battle Tower, complete the Hoenn Pok�dex with 200, and register 90 field trainers in Match Call.

1. Beat all stages of the Pokemon Contest (Normal, Super, Hyper, and Master). Once you do, an artist should come out saying that he painted your Pokemon better than usual, then he says that it belongs in the musuem, so when he asks you if the musuem is holding an open exhibit, if you want one painting in the room and more people in the musuem, say yes.
2 and 3. To get one star and a Green Card, beat the Pokemon League. And, to get two stars and a Bronze Card, do one of the following: beat all five master competitions in the Pokemon Contest, obtain all gold symbols in the Battle Frontier, or catch all 200 (or 202) Pokemon of the Hoenn Pokedex. To get three stars and a Silver Card, do two of the above. To get all four stars and a Gold Card, do all of the above.

1 by completeing all the master rank contests and letting the artist go to the museum with his painting

2 don't know

3 don't know

1. Win the Pokemon Contest Master Rank two times and the artist that makes all the paintings will make a really cool painting and would want to know if he could hang is somewhere for everyone to see.

2. You don't get any stars for your trainer card.

3. Bronze, Copper, silver, gold.
-Become Pokemon league Champion
-Complete the Hoenn Pokedex
-Collect all the gold symbols in the Battle Frontier
-Win one ribbon in all five of the Master Rank Pokemon Contests.
Do oneof the above for Bronze.
Do two for Copper.
Do three for silver.
Do all four for Gold.

Please rate and verify this.

1) You need to win the Lilycove Master Contests (for each catagory to get a painting) with 5 stars or more and you'll get a picture of the winning Pokemon in the museum. Get one each in all 5 catagories and you'll also get the statue!!
2)Beat E4, Have 1,000 battles on Match Call, Get 100 wins at Battle Tower, Fill Hoenn Pokedex, Fill all spaces in Art Museum (see Q1).
3) Do these things:Beat E4, Complete Hoenn Pokedex, Collect all Gold symbols in Battle Frontier, Fill spaces in Art Museum (see Q1). Your card will go from Bronze, to Copper, to Silver ,To GOLD as you do each task in any order possible(obviously you need to beat E4 to get to Battle Frontier or finish Pokedex!) When you battle or trade records with another trainer with the wireless or link cable you can check out their card and see what color it is, and visa-versa!
So, basically, it's the same thing to get stars and change card colors, except the 1,000 match call battles and getting 100 wins at the Battle Tower. I'm pretty sure this is the correct info for stars-I KNOW it is for the card color changes.
Here's some extra info since you like to collect things:
How To Collect Ribbons:
1)Beat E4and enter Hall of Fame(any Pokemon you do it with will get one!)
2)Win the Master Rank Title in a Pokemon Contest
3)If you win the Master Rank contest with an exceptionally high score(5 or more stars, I believe), the artist will give your Pokemon a Ribbon(and put it's picture in the museum, too)
4)Win against 50 trainers at the Battle Tower in the Battle Frontier
5)The woman next to the Energy Guru in Slateport City market will give your Pokemon a ribbon if it's strong enough.
Also, if you max out a Pokemon's condition(ex:Beauty, Tough, Cool, etc), you can get the corresponding color scarf from the guy on the couch in the Lilycove Trainer's Fan Club, so there's 5 scarves you can collect, too, (besides the silk one you get in Dewford) that will raise the Pokemon's condition in that color.(i.e. Blue Scarf-makes your Pokemon's Beauty condition higher and so on)
Happy Collecting!

1.win the Pokemon contest on master rank

2.defeant the Pokemon league and hatch an egg

3.I don't think you can,sorry

Hope I help