Using my telescope PowerSeeker 70EQ.?

The only eyepiece which is usable is the 20 mm. Both the 3x Barlow and the 4mm eyepiece give magnifications too high for the size of the telescope. Using the 20 mm eyepiece, you may be able to see that Saturn has rings, but that's about it; Mars will be nothing but a tiny dot. The diagonal (I think what you called a "periscope") should always be used for comfortable viewing. You might add a 7 mm or 9 mm eyepiece to give you a bit more magnification, but the small size of your telescope puts an upper limit of around 100x on the magnification your telescope is capable of.