There is no such thing as "practical training visa." Students remain on their F-1 visa while they are doing their optional practical training.
No. Many students apply for post-completion practical training before they have actually received a job offer. However, it is important to start looking for work opportunities as early as possible since it usually takes students longer than they anticipate to find a position.
Some students want to do part-time training for a few quarters while they are still taking classes full-time, then use the remainder of their training full-time after they graduate. Others use full-time practical training to work for three months during their summer vacation. Dividing up practical training in this way is allowed, to a maximum of 12 full-time months, however each period of training requires a separate application along with the $340 fee (subject to change by BCIS). You cannot divide you time for post-completion.
Yes and no. You can take courses that are non-matriculating towards another educational level. You may be able to take incidental, non-matriculating classes on a part-time basis. Please check with the ISSC before you make any decisions on study during your practical training period.
Once the EAD card has been issued, there is no way to cancel it.
You have 60 days after the end date on your EAD card to leave the country, start a new degree program, or change to a new visa status. You cannot work during the 60 day grace period. You are free to travel within the United States, but you should not expect to be able to return to the U.S. with your EAD card and I-20 if you leave the country during these two months.
Yes and no. You will be eligible to apply for another 12 months of work authorization only if you change your degree level, i.e. Bachelor to Master's and Master's to Doctorate.
There is no way to extend your 12 months of practical training. Some students have been successful in getting an employer to sponsor them for a different visa, usually an H-1B visa, allowing them to continue to work here for a few years. The process is somewhat complicated however, and usually either the employer or the student will need to hire an immigration attorney
If you are applying for post-completion the application must be received by the BCIS Nebraska Service Center before the last day of your last quarter of degree completion.