I looked it up. Your sentence may be o.k., but I haven't heard or seen "rightward" used that way.
Or you could say : I looked towards the right.
Yes.
Yes, the sentence "I looked rightward" is grammatically correct. It is a sentence in the past tense where the subject "I" performed the action of looking in the direction of the right. The word "rightward" is an adverb that describes the direction of the action. However, it is worth noting that the more commonly used form is "I looked to the right."
