is it equity?or shares? or dividend is the best to offer and how many % it will be?
Shares and equity are the same. Equity means a part of the company which is actually made by handing them over shares if the company has shares (not all forms have).
Dividend, on top, is the payout of profits according to shares. So, you have a million in profit, pay out 100,000 USD as dividend and it is divided by equity holders according to the number of shares each has.
If its shares, how many shares of my future business will have?
When you cook, how many meals do you cook? We can not know, you do. A company has as many shares as the owners / founders declare. I can start a company with 100,000 shares or with 100 million shares, all that is my decision when I start it. Naturally, the value of the shares fluctuates too - nothing is fixed here, it all depends on what the company owners decide.
how many % to give? and how long?
% is to be negotiated, but "how long" is meaningless. Either you want a loan, or an investor. An investor is not "how long"", it is you give him shares in return for money for the business. When I buy 10,000 microsoft shares there is no "how long". I own them, they are not borrowed.
A book about the basics of running a business is a needed read before dealing with more money than a house has - or you may end up in court.
What is the great offer for a seed investor?
One that makes him 3 million within 5 to 10 years potentially. Minimum.
Please, take some beginner classes how businesses operate or you get yourself into deep legal trouble.