Difference of DTI and SEC Registrations

DTI is for single proprietor while SEC is for partnerships, incorporated and corporation.

You can use DTI for importation as long as you completed all the necessary documents and business permits.

Thanks Kreo,,,,is it also true that SP businesses have bigger tax requirements than corporations?

I think you may want to consult a lawyer for this venture. When are you planning to push through with this?

Carosel, 
If you are still a citizen of the Philippines, your options are much broader than the average expat.  Nonetheless, you will need to give very serious thought about your organization type and structure along with your entry port region and local business units that can aid in selected tax advantages. 

Much of what you need to learn does not require an atty and it is in your best interest to learn much on this topic before you spend 1 peso. 
Here are just a few examples on what to learn about: 

Learn about - The Board of Investments (BOI) under the Omnibus Investments Code (OIC) Note: The applicant must be a natural-born Philippine citizen or 60% Fil corp.

Learn about -Philippine Economic Zone Authority (PEZA) & related tax and non-tax incentives.

Learn about - If it will be a preferred project under the existing Investment Priorities Plan (IPP).

Learn about - If your business will qualify for Tax incentives with a six-year income tax exemption from the start of the enterprise's commercial operations for pioneer establishments, as well as a four-year income tax exemption for non-pioneer ones. This income tax holiday can even be extended depending on the BOI's approval up to a maximum of eight years.

Best wishes