Try a soft reset by holding both volume buttons, power and home for 15sec. If problem persists you have have a hardware problem like the screen. Last resort would be a hard reset before investing in a new screen.

No problem new front cam flex should work

Yes you will need to perform a hard reset. Sometimes clearing the cache will help but it sounds like the android os crashed. Turn off the device. Press and hold down the Volume up and Power keys at the same. When the Alcatel startup screen appears, release the Power key. When the Android system recovery screen appears, release the Volume up key. Use the Volume up/down key to highlight wipe data/factory reset. Press the Power key to select. Press the Volume down key to select "Yes -- delete all user data". Press the Power key to select. Press the Power key to select Reboot system now.

Yes it should be fine. It should reactivate after powering on and provision with your current carrier. Most phones will powercycle after activating.

Try a new front cam flex cable with mic. The connection for the earpiece might be bad on the flex cable. Hence why the two earpieces are not working.

Either the lcd has a hairline crack and blacked out. Or the connection to main board from lcd/screen is loose.

If the connector where the charging port/mic connect to main board has debris it can cause the issue. Double check the connector.

Do you have another battery to test it with? Also double check the terminals.

Try cleaning/clearing the headset jack with canned air. If this does not resolve you might have to hard reset the device.

Try checking the connection area for the flex cables. Check for debris keeping the connection from being solid. If this still does not work it may be the flex cable which depending on where the part is coming from try another seller or a reputable wholesaler like Etrade Supply.