Getting All Endorsements?

1, yes you can take all knowledge test at the same time at DMV with the exception of HazMat which requires several steps (enroll online, fingerprints, background check, TSA approval, knowledge fees, about $100-200 in fees.

2 I don't think failing an endorsement prevents getting the permit, but you need General, Combination, and air-brakes for an 18-wheeler. So failing one of those may be a problem.

3 i don't know.

4 you need to test in a vehicle appropriate for bus and one appropriate for 18-wheeler, but not tanker or double trailer.
GET TANKER. NO MATTER WHAT

 

IMO, the smart way to do this is find the company to work for AND THEN decide when,where,how to get the CDL. If you do it in that order you don't waste time, effort, money getting the CDL in the way that works for several companies you would never work for.

Half of all trucking companies that hire newbies offer Tuition Reimbursement. EVERY CDL school will find someone to loan money for school, if you need it. A number of trucking companies have their own school. The difference between companies that fit you and the dozens or hundreds that don't fit YOU is enormous.

You wouldn't first start driving and then later decide where you were going. If you did you could be wasting time and fuel.

This is not something that can be decided by reading want ads or company web pages. You ask drivers working at a company if you want info on that company. Nothing else is half as useful. Make the company put you in contact with drivers and/or ask drivers here and at truck stops about the company.

 

For the clp you just need the general/combo and air brakes. If you choose to get your endorsements you can get them at the same time as the clp or you can study and get them when you graduate to your cdl. Here in Michigan you can take these tests 1x per day until you pass them once you pass them they stay.
Now Michigan charges a 25$ update fee plus 5$ for the endorsement. I’m not sure how your state does it but instead of paying that update fee all those times. pass all the tests for endorsements that you want then do it all at once if possible