I don’t know what exactly you are trying to do. Please be more brief,
Anyways, wrapper class instance can be added easily in list by these few statements.
List<wrapperClass> wrapClassList = new List<wrapperClass>();

wrapClassList.add(new wrapperClass(arg1, arg2)());

Goto App Manager > select lightning app > add your lightning page > finish

It is done to improve the readability and cleanliness of the code

Recursive Trigger problem occurs usually on update Trigger, you have solve the problem by adding this code :

public class CheckRecursive {
    private static boolean run = true;
    public static boolean runOnce() {
        if(run) {
            run = false;
            return true;
        }
        else {
            return run;   
       …

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Avoid the inner Queries, follow the best practices

For the Aggregate Query you have AggregateResult class in apex

Example

for(AggregateResult ar : [select count(Id), AccountId
                          from Contact 
                          where AccountId in :accset
                          group by AccountId
                          having count(Id)>2 ])
{
    contList.add(new Contact(Id…

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Go to Quick Find, type duplicate Rules , untick the old rules or create a new Rule which defines duplicate not allowed

set<id> accountids = new set<id>();
for(Contact con : Trigger.New) {        
     accountids.add(con.AccountId);
}
List<account> accList = [ select Name, (select AccountId, firstName, lastName from Contacts where AccountId =: accountids limit 1) from Account ];