Overview:
-Estimated achievement difficulty: 4/10
-Offline: 35 (1150)
-Online: 5 (100)
-Approximate amount of time to 1250: 100 hours
-Minimum number of playthroughs needed: 1
-Number of missable achievements: None!
-Glitched achievements: None!
-Do cheat codes disable achievements?: No cheats

This is not a hard game by any means. It's time consuming, but not hard. The 100% collection achievement might have you feeling frustrated, but most of the time you will have no problems. Beautiful Katamari is a fun and wonderfully weird game that will keep completionists busy for quite some time.

Introduction:
Welcome to the Road Map for Beautiful Katamari, the Xbox 360 exclusive game of the katamari-series.
The game has a total of 40 achievements with a value of 1250. To get all achievements in this game you will need to download 7 extra stages at a cost of 1500 ms points:
* Mechanical Katamari (200 MSP)
* Dangerous Katamari (200 MSP)
* Perfectly Sized Katamari (300 MSP)
* Milky Way Constellations (200 MSP)
* The Weaver Girl (200 MSP)
* Shopping Spree (200 MSP)
* High-Calorie Katamari (200 MSP)

Some of the achievements are quite time consuming, and on top of it all we have the 100 Hours playtime achievement. On the bright side though, you will technically be working on 5-10 achievements at the same time just by playing through a single stage.
Even though its time consuming it's not hard. If you follow the Achievement Guide and this Road Map and make good use of the forums and you should be done in no time (figuratively speaking).

Step 1: Save the Universe, and Do It Fast!
The first thing you should do is finish the main story. When you complete one stage a new one will be unlocked. The gameplay might be hard at first, but you'll soon get the hang of it. By finishing a stage you will also unlock the Time Attack mode for that stage. When all the original (the non-DLC) stages are finished you should play the Time Attack on each stage where it's available.

Step 2: Family Gathering
Now it's time to start collecting! To collect all presents and cousins you need the DLC mentioned in the introduction. HERE is a guide to all presents and cousins made by the one and only Pants, and HERE is a collection of excellent walkthroughs made by ZoopSoul.

Step 3: The Calm Before the Storm
Now's a good time to mop up all smaller achievements we have overlooked so far.
Manic Roller, Responsible Roller and Non-stop Roller are easy to do if you've unlocked Eternal Mode for a stage (by getting 100 or more points in Normal Mode).
Next we go online and start unlocking the few online achievements this game has.
The online achievements are like the rest of the game; easy but time consuming. I recommend playing the House-level over and over since it's the shortest one (60 sec).
Don't worry if you keep losing; even if you lose almost every match you will probably still have collected 1,000 cookies before you have played 50 online games.

Step 4: The Pain
Now when everything else is done we'll go for the big, time consuming achievements. Start searching the stages for new items for the Collection. The name of the new items are displayed in rainbow colors when you roll them up. The easiest way to find all items on a stage is to unlock Eternal mode. When you have collected about 97% of all the items, it's a good idea to make a checklist of the remaining ones.

Use THIS thread when making your list. This makes things easier when using THIS thread. Remember to search before you post and ask. Search both for the group with number, e.g Plants 1-2-1, and the name of the object; Big Tree. HERE is another useful link for finding 100% of the collection.

While searching for all items you will get most of the playthroughs necessary for the Katamari Fan/Lover achievements (if you don't play on Eternal Mode). The remaining ones are easily completed by playing the downloadable stage Instituto Exactamundo over and over.

Astronomic Katamari can be achieved on both Chatéau Notre Desir and Schloss Kosmos. Note that to get the achievements on Chatéau Notre Desir you must both roll a big enough katamari AND collect more memories than your previous best. Also note that the more times you have completed Normal Mode on a stage, the bigger chance you have of unlocking Astronomic Katamari, since each Normal Mode play adds an extra planet/comet/thing to roll up in space.

Last but certainly not least we have the 50 and 100 hours of playtime achievements. Just leave the game running in the Princedom and wait. Even if you reach 50 or 100 hours, the achievement will not unlock untill you complete a stage, so be sure to play a stage every now and then just to see if you've gotten it.

Conclusion:
If you are missing any achievement at this point, it's probably the 100% Collection or the 50/100 hours playtime since they are secret achievements. Just check steps 1-4 again and you should see what you're missing.