"Forward" and "backward" are just ways of describing time. If time is an axis, just like a physical point, then it's like having positive and negative time, with 0 being the present. It's kind of hard to verbally describe.

You could interchange the two words and a system could still exist, and particles could still move.

Time is the bend of space, an observed and natural phenomenon. The "freezing time" you speak of is irrelevant, as "freezing time" is literally putting it to absolute zero Celsius. Time cannot be stopped, but it can be bent, as this occurs naturally. I'm not saying man can do it, simply that it occurs in nature. Something like molecular speed is NOT time.

If you assume that time is like water than yes it is never ending. But if you assume that time moves like waves (If the water was covering the entire surface of a planet). Assuming the principles of time work for this scenarios than time's present requires past and future requires past. By altering this wave you in theory could slow it down but no i don't think you freeze it. As in water if you freeze it, water still moves on some level.