Yes, Ghostly Touch and Hidden Strings can tap or untap (useful politically) your opponents lands.

On ramp/Mana rocks: Most decks have at least a few but it depends on how it plays. You are only running 31 lands and (I think) two Mana dorks, and 1? Mana rock which is low. However, your average CMC is 2.66 which is also pretty low. I'd add a Sapphire Medallion if you have one laying around. Otherwise it should be fine. When you play it, if you seem to get Mana screwed too often then add Sky Diamond, Midnight Clock (great at refilling your hand) or other 2 cost rocks but you shouldn't need to many with how cheap everything in your deck is.

Since Mana Leak is your jam:

Wizard Replica, Spiketail Hatchling, and Cursecatcher work well-ish on offense with your commander.

Power Sink is fun when you don't want them casting anything else.

Library of Leng essentially gives you unlimited hand size since you never have to discard down to 7 (or whatever your handsize is). You simply don't discard since you don't have a discard phase, it does not technically effect your hand size.

It also works well when some one casts Windfall or even your own effects like cycling or cards like Frantic Search. You may also discard what you don't want to your graveyard but discard what you do want to the top of your library to draw again. It tends to be a strangely useful and underapreciated card.

I'd swap Graceful Adept for Library of Leng. Cheaper, harder to remove, and added bonus against discard.

Cancel for any other counterspell. There are plenty of 1UU with upside such as personal favorite of mine, Admiral's Order. Rewind, Dissipate, Unwind and Negate are also solid budget options. Personally not a fan of Mana Leak-esk counters since if an opponent has a ton of Mana, they become useless. Also, Defense Grid is an odd choice for a blue deck since it hurts your own counters on your opponents turn.

I'd consider trying to find room for a card or cards like Coastal Piracy, Bident of Thassa, and The Indomitable.

Single protection to consider, Mithril Coat is amazing, Commander's Plate always pulls a ton of weight in mon color (may hurt commander's unblockable agaimst another monoblue but otherwise really helps), Dive Down not amazing, just a pet card when it was in standard.