You may look at these face-down exiled cards any time you wish. No other player may look at the face-down cards you exiled with Lobelia, Defender of Bag End, even if another player takes control of it.

If Lobelia, Defender of Bag End leaves the battlefield, and later another Lobelia, Defender of Bag End enters the battlefield, it is a new object (even if the two were represented by the same card). You can't play cards exiled by the original Lobelia, Defender of Bag End with the second ability of the new Lobelia, Defender of Bag End.

If the spell has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

To play a card using the permission granted by the first mode of Lobelia, Defender of Bag End's activated ability, you must still follow any timing restrictions and permissions, including those based on the card's type. For instance, you can play a land from exile this way only during your main phase while the stack is empty, and only if you have an available land play remaining for the turn.

If you cast a spell "without paying its mana cost", you can't choose to cast it for any alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, those must be paid to cast the spell.