How an English learner can be sure that in writing paragraphs he is using the correct form of object
The type of object a verb can take depends heavily on the verb's meaning. This is why the dictionary does not explain, because you should select a type of object that works with verb's meaning.
You can Google for word lists using search terms like "Words that take gerunds as objects", etc. However, I don't think there many verbs that will absolutely not work with concrete nouns as objects (to think is one though.)
can I always use intransitive verbs as transitive verbs
No. For example.
Die cannot take an object and make any sense.
- Not all transitive verbs can work intransitively.
I hit Mark with the ball.
I hit. (Does not make sense unless the object is heavily implied from context.)
- Some verbs change meaning depending on whether there is an object or not.
She walks to the park. (She is traveling by foot to the park.)
She walks him to the park. (She is either helping an old guy walk to the park or leading a dog on a leash to the park.)
- Some verbs are reflexive if no object is specified. In this case the real object is myself, himself, etc.
I washed. (Same as saying "I washed myself.")
I washed the car.
- Many verbs have phrasal variations (i.e. consist of more than one word) that have a different transitive-ness.
I struck the enemy with a sword.
I struck out of the ball game. ("Strike out" is a phrasal verb)