It depends on the situation. Let me give you some example sentences first.
(Example 1) “Two different items” You have an orange and an apple in your hand.
こっちはみかんです。そして、こっちはりんごです。(KOCCHI WA MIKAN DESU. SOSHITE, KOCCHI WA RINGO DESU.) This one is an orange and this one is an apple (you are pointing at each object.)
In this situation, こっち (KOCCHI) means “this one/this out of two items”.
(Example 2) “Two same items” You have two apples in your hand. One is delicious and the other one is not.
こっちはおいしいです。でも、こっちはおいしくないです。 (KOCCHI WA OISHII DESU. DEMO, KOCCHI WA OISHIKUNAI DESU) = This one is good. But, this one (the other one) is not good.
こっち (KOCCHI) means “this one/this out of two items” in this sentence as well.
(Example 3) “more than two same items” How about when you have four apples in front of you? Two of them are delicious and the other two are not so delicious.
こっちはおいしいです。でも、こっちはおいしくないです。 (KOCCHI WA OISHII DESU. DEMO, KOCCHI WA OISHIKUNAI DESU) = These (two) are good. But, these (other two) are not good.
As you can see, the above sentence is the same as example 2. The two delicious apples and the other two not-so-delicious apples are considered as two different groups. Therefore, こっち is used in the sentence. (The English translation for こっち can be “two of these.”)
As for your second question, if you are just saying that “these are apples” (as a group/ without comparing them), you can use これ (KORE) as below.
これはりんごです。(KORE WA RINGO DESU) = These (two) are apples.