Here are the rules on Mounted Combat.
First of all, half-orcs (and other Medium creatures) can't mount regular wolves (or other Medium creatures):
A willing creature that is at least one size larger than you and that has an appropriate anatomy can serve as a mount, using the following rules.
A wolf is a Medium creature. A Dire Wolf or Winter Wolf could serve as a mount (assuming you managed to tame it), as they are both Large. (Half-Orcs, like most player races, are Medium.)
Secondly, here are the only rules on dismounting a creature:
Once during your move, you can mount a creature that is within 5 feet of you or dismount. Doing so costs an amount of movement equal to half your speed. For example, if your speed is 30 feet, you must spend 15 feet of movement to mount a horse. Therefore, you can’t mount it if you don’t have 15 feet of movement left or if your speed is 0.
If an effect moves your mount against its will while you’re on it, you must succeed on a DC 10 Dexterity saving throw or fall off the mount, landing prone in a space within 5 feet of it. If you’re knocked prone while mounted, you must make the same saving throw.
If your mount is knocked prone, you can use your reaction to dismount it as it falls and land on your feet. Otherwise, you are dismounted and fall prone in a space within 5 feet it.
There are no rules for combining a dismount with an attack. Your DM could house-rule otherwise, but there's no inherent benefit to dismounting as you attack by the rules as written.
Also, if I leave my Lance in the body (like dropping it) and use my bonus action to draw my longsword, since I have extra attack, can I still attack with the longsword?
If you are of a class that has the Extra Attack feature and are high enough level to make multiple attacks as part of your Attack action, then this would be possible. You would have to make your first attack with an already-drawn lance (note that if you attack with a lance, you do so at disadvantage if the target is within 5 feet of you), drop/let go of the lance, use your free object interaction for the turn (not a bonus action) to draw the longsword, and then attack with it.
This Sage Advice confirms that you can use different weapons for the multiple attacks granted by the Extra Attack feature, as does this one. It's also confirmed in the Sage Advice Compendium:
When you use Extra Attack, do you have to use the same weapon for all the attacks?
Extra Attack imposes no limitation on what you use for the attacks. You can use regular weapons, improvised weapons, unarmed strikes, or a combination of these options for the attacks.