There won't be a further delay because the motion to dismiss will be granted. This is because you filed the lawsuit pro se. Next, you'll be suing yourself for legal malpractice.

No, when he gets a new attorney he cannot start over on discovery and motions.

You don't get to dictate who represents the other side, or how, nor is it any of your concern. Your concern should be on avoiding your case being dismissed on the merits or for failure to follow required procedures.

No amount of free 'tips and hints' from here or elsewhere are going to effectively help you in your legal case as a pro per. If you don't know how to represent yourself effectively against experienced attorney[s] intending to 'beat you' and get your case thrown out, then hire an attorney that does, who will try to get a reasonable settlement, or take it to trial if appropriate. If you couldn't find any attorney willing to take the case, you should rethink your estimation of its validity and value.

If this is in SoCal courts, and if you are serious about hiring counsel to consult and give you a 'second opinion' in this, or even to consider representing you if the case has merit and value, feel free to contact me to arrange.

There could be further delay, but it would not be automatic. A substitution of an attorney would not trigger anything legally. The new attorney may, however, request additional time to get up to speed. She would ask you for more time to respond or to move a court date back. If you denied this request the attorney would probably go the judge. Depending on the status of the case, the judge may grant these requests regardless of your denial. You may be better off just allowing the additional time (if it is reasonable). Otherwise, you are going to have to go to court and argue why it is not.