Just get a H1B visa and company has no job for me, so I can´t activated it

Your use of the words "activate the visa" constitutes a misunderstanding of what is happening here. In fact, your H-1B visa simply allowed you to enter the U.S. and begin working for your employer. Since you have presented yourself as available for employment, your H-1B sponsor-employer is required by law to pay you for any periods of time spent "on the bench", that is for periods that it does not put you to work. The only way for an employer to avoid that obligation is by withdrawing the petition with the USCIS. The plan to pay you and then have a new company file a new petition for you may permit you to begin working for the company "B". But that company will need to file an H-1B petition to allow you to change employers. As for your last question, if the initial sponsor does not withdraw its petition, then you should be able to leave the country and return using the visa when it has work for you.

One cautionary note is that USCIS is conducting fraud investigations of many H-1B sponsors. One of the areas it is looking into is where employers bring H-1B workers to the U.S. when they do not have work available for them. You and your company may want to receive legal counsel regarding these investigations and the employer's legal obligations, since it could impact the ability to utilize the H-1B visa program in the future.